ASP.NET ChangeConflictException; "No row found or changed"

I cant resolve this error.  I'm using Linq to SQL and I can't get this to resolve.  I'm the only one touching this data so it's not a matter of more than one person hitting the data.

using System;
using System.Configuration;
using System.Data;
using System.Data.Linq;
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 CPMS_DAL;
 
public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        CPMSDataContext db = new CPMSDataContext();
        tbl_Account Account = db.tbl_Accounts.Single(ua => ua.Company_Name == "Test_Company");
 
        ViewState["AcctID"] = Account.AcctID;
        ViewState["version"] = Account.version;
        ViewState["CreateDate"] = Account.CreateDate;
    }
 
    protected void BtnUpdate_Click(object sender, EventArgs e)
    {
        //Create an Account object and set the properties
        tbl_Account Account = new tbl_Account()
        {
            Company_Name = "Testing_company",
            UpdateDate = DateTime.Now,
            UpdateByID = 55
        };
        Account.AcctID = Convert.ToInt32(ViewState["AcctID"]);
        Account.version = (Binary)ViewState["Version"];
        Account.CreateDate = Convert.ToDateTime(ViewState["CreateDate"]);
        CPMSDataContext db = new CPMSDataContext();
        db.tbl_Accounts.Attach(Account, true);
 
        db.SubmitChanges();
        
    }
   }

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