help fix an error in asp

i have posted a code below that seems to be working half way. i am a newbie to asp and therefore need it to be explained as simplistically as possible.

the problem is: as u will see there are data that has to go in multiple db's. the data seems to go into the first 2 db's and then jumps to the exception. pls assist.

using System;
using System.Collections;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.IO;
using jb_datamanipulate;
using System.Web.Mail;
using Winthusiasm.HtmlEditor;

public partial class superadmin_Job_master : System.Web.UI.Page
{
    cscSQLdata objData = new cscSQLdata();
    string strConnection = "";

    protected void Page_Load(object sender, EventArgs e)
    {
       if (!IsPostBack)
        {
        //    bindCountry();
        //    bindCountry2();
        //    bindCity();
        //    bindCity2();
        }
    }
    

protected void  btnApply_Click(object sender, EventArgs e)
{
    try
    {
        strConnection = ConfigurationManager.ConnectionStrings["ConnStringpkt"].ToString().Trim();
        DataSet ds = new DataSet();
        objData.connectionstring = strConnection;

        string strPassword;
        strPassword = RandomNumber(1000, 9999).ToString();


        ds = objData.metcscdataset("select * from Profile where LoginId = '" + txtLoginID.Text.ToString() + "'", "jobportal");
          if ((ds.Tables[0].Rows.Count > 0))
          {
              divmsg.Visible = true;
              lblmsg.Text = "Sorry! Already UserName exist, Username must be unique";
          }
          else
          {
              DataSet ds2 = new DataSet();
              DataSet ds3 = new DataSet();
              DataSet ds4 = new DataSet();
              DataSet ds5 = new DataSet();
              
              int MemID = 0;

              objData.metcscgetstring("Insert into Profile(LoginId, Password, EMailId, FName, LName, MName, FatherName, MotherName, Address, CityId, CountryId, ZIP, DOB, Sex, Nationality) values('" + txtLoginID.Text.ToString() + "','" + strPassword.ToString() + "','" + txtEmail.Text.ToString() + "','" + txtFirstName.Text.ToString() + "', '" + txtLastName.Text.ToString() + "', '" + txtMiddleName.Text.ToString() + "', '" + txtFather.Text.ToString() + "', '" + txtMother.Text.ToString() + "', '" + txtAddress.Text.ToString() + "','" + int.Parse(ddlCity.SelectedValue.ToString()) + "', '" + int.Parse(ddlCountry.SelectedValue.ToString()) + "', '" + txtZip.Text.ToString() + "', '" + txtDOB.Text.ToString() + "', '" + int.Parse(ddlGender.SelectedValue.ToString()) + "', '" + int.Parse(ddlNationality.SelectedValue.ToString()) + "')");
              //'" + txtRelegion.Text.ToString() + "'
              
              ds2 = objData.metcscdataset("Select max(MemId) as mid from Profile", "jobportal");
              if (ds2.Tables[0].Rows.Count > 0)
              {

                  MemID = int.Parse(ds2.Tables[0].Rows[0]["mid"].ToString());
              }
              MemID = 0;
              objData.metcscgetstring("Insert into Acedemics(MemId, FromDt, ToDt, FinalResultDt, Grade, Institute, University, Percentage) values(" + MemID + ",'" + txtFromDt.Text.ToString() + "', '" + txtToDt.Text.ToString() + "', '" + txtFinalResult.Text.ToString() + "', '" + int.Parse(txtGPA.Text.ToString()) + "', '" + txtInstitute.Text.ToString() + "', '" + txtUniversity.Text.ToString() + "', '" + int.Parse(txtPercentage.Text.ToString()) + "')");
              
              ds3 = objData.metcscdataset("Select max(MemId) as mid from Academics", "jobportal");
              if (ds3.Tables[0].Rows.Count > 0)
              {

                  MemID = int.Parse(ds3.Tables[0].Rows[0]["mid"].ToString());
              }

              objData.metcscgetstring("Insert into ExpDetails(MemId, CompanyName, CompanyAddess, TechWorked, FromDt, ToDt, LastPosHeld) values(" + MemID + ",'" + ddlCompName.SelectedItem.ToString() + "', '" + txtCompanyAddress.Text.ToString() + "', '" + ddlTechnology.SelectedItem.ToString() + "', '" + txtStDt2.Text.ToString() + "', '" + txtStDt3.Text.ToString() + "', '" + int.Parse(ddlRole.SelectedValue.ToString()) + "')");

              int ExpId = 0;

              ds4 = objData.metcscdataset("Select max(ExpId) as expid from ExpDetails", "jobportal");
              if (ds4.Tables[0].Rows.Count > 0)
              {

                  ExpId = int.Parse(ds4.Tables[0].Rows[0]["expid"].ToString());
              }

              objData.metcscgetstring("Insert into WorkDetails(ExpId, PrjName, PrjDesc, RolePlayed, TechUsed) values(" + ExpId + ",'" + txtProject.Text.ToString() + "', '" + txtProjectDesc.Text.ToString() + "', '" + ddlRole.SelectedValue.ToString() + "', '" + ddlTechnology.SelectedItem.ToString() + "')");



              objData.metcscgetstring("Insert into EmployersLocation(CompanyId, Address, CityId, ContryId) values('" + int.Parse(ddlCompName.SelectedValue.ToString()) + "', '" + txtCompanyAddress.Text.ToString() + "','" + int.Parse(ddlCity2.SelectedValue.ToString()) + "', '" + int.Parse(ddlCountry2.SelectedValue.ToString()) + "')");

              int CompanyId = 0;

              ds3 = objData.metcscdataset("select CompanyId as cid from EmployersLocation where EmlrLocId =(select max(EmlrLocId) from EmployersLocation);", "jobportal");
              if (ds3.Tables[0].Rows.Count > 0)
              {

                  CompanyId = int.Parse(ds3.Tables[0].Rows[0]["cid"].ToString());
              }
              
              objData.metcscgetstring("Insert into Employers(CompanyId, CompanyName, Address, CityId, ContryId) values(" + CompanyId + ", '" + ddlCompName.SelectedItem.ToString() + "','" + txtCompanyAddress.Text.ToString() + "'," + int.Parse(ddlCity2.SelectedValue.ToString()) + ", " + int.Parse(ddlCountry2.SelectedValue.ToString()) + ")");

          }

    }

    catch (Exception ex)
    {
        divmsg.Visible = true;
        lblmsg.Text = ex.ToString();
    }
}
private int RandomNumber(int min, int max)
{ 
    Random random = new Random();
    return random.Next(min, max);
}
//void bindCountry()
//{


//    //DataTable dt = new DataTable();
//    strConnection = ConfigurationManager.ConnectionStrings["ConnStringpkt"].ToString().Trim();
//    DataSet ds = new DataSet();
//    objData.connectionstring = strConnection;

//    ds = objData.metcscdataset("select * from Profile", "jobportal");

//    if ((ds.Tables[0].Rows.Count > 0))
//    {
//        ddlCountry.DataSource = ds.Tables[0].DefaultView;
//        ddlCountry.DataValueField = "CountryId";
//        ddlCountry.DataTextField = ddlCountry.SelectedItem.ToString();
//        ddlCountry.DataBind();
//        ddlCountry.Items.Insert(0, new ListItem("(Select)", "0"));
//        // u can also fetch data from this dataset aslo
//    }
//    else
//    {
//        ddlCountry.DataSource = null;
//        ddlCountry.DataBind();
//    }
//}

//void bindCountry2()
//{


//    //DataTable dt = new DataTable();
//    strConnection = ConfigurationManager.ConnectionStrings["ConnStringpkt"].ToString().Trim();
//    DataSet ds = new DataSet();
//    objData.connectionstring = strConnection;

//    ds = objData.metcscdataset("select * from EmployersLocation", "jobportal");

//    if ((ds.Tables[0].Rows.Count > 0))
//    {
//        ddlCountry2.DataSource = ds.Tables[0].DefaultView;
//        ddlCountry2.DataValueField = "ContryId";
//        ddlCountry2.DataTextField = ddlCountry2.SelectedItem.ToString();
//        ddlCountry2.DataBind();
//        ddlCountry2.Items.Insert(0, new ListItem("(Select)", "0"));
//        // u can also fetch data from this dataset aslo
//    }
//    else
//    {
//        ddlCountry2.DataSource = null;
//        ddlCountry2.DataBind();
//    }
//}
//void bindCity()
//{


//    //DataTable dt = new DataTable();
//    strConnection = ConfigurationManager.ConnectionStrings["ConnStringpkt"].ToString().Trim();
//    DataSet ds = new DataSet();
//    objData.connectionstring = strConnection;

//    ds = objData.metcscdataset("select * from Profile", "jobportal");

//    if ((ds.Tables[0].Rows.Count > 0))
//    {
//        ddlCity.DataSource = ds.Tables[0].DefaultView;
//        ddlCity.DataValueField = "CityId";
//        ddlCity.DataTextField = ddlCity.SelectedItem.ToString();
//        ddlCity.DataBind();
//        ddlCity.Items.Insert(0, new ListItem("(Select)", "0"));
//        // u can also fetch data from this dataset aslo
//    }
//    else
//    {
//        ddlCity.DataSource = null;
//        ddlCity.DataBind();
//    }
//}

//void bindCity2()
//{


//    //DataTable dt = new DataTable();
//    strConnection = ConfigurationManager.ConnectionStrings["ConnStringpkt"].ToString().Trim();
//    DataSet ds = new DataSet();
//    objData.connectionstring = strConnection;

//    ds = objData.metcscdataset("select * from EmployersLocation", "jobportal");

//    if ((ds.Tables[0].Rows.Count > 0))
//    {
//        ddlCity2.DataSource = ds.Tables[0].DefaultView;
//        ddlCity2.DataValueField = "CityId";
//        ddlCity2.DataTextField = ddlCity.SelectedItem.ToString();
//        ddlCity2.DataBind();
//        ddlCity2.Items.Insert(0, new ListItem("(Select)", "0"));
//        // u can also fetch data from this dataset aslo
//    }
//    else
//    {
//        ddlCity2.DataSource = null;
//        ddlCity2.DataBind();
//    }
//}

}

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