ListBox Selected Value

1: Set the breakpoints and debug to see if right value is assigned to the LinkID parameter
2: move try/finally inside if
3: Add catch block
4: If you have access to SqlProfiler then try to setup a trace and see if the command is executed and the value passed.

Which method is the code you posted above contained within?

It seems to be a null value. However, the listbox does have values when the Page is loaded

      <option value="13">Change Password</option>
      <option value="14">New User</option>
      <option value="15">Delete Users</option>

Make sure your ListBox is not re-binded during postback...
i.e. place your listbox binding code in this block...

if(!Page.IsPostBack)
{ //Bind listbox
}

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Or share your code-behind on how you are binding the data to listbox.

I made a few changes and it still does not work. Here is the current way I am binding the ListBox and trying to enter the values in a table.  

if (Page.IsPostBack == true)
        {
            string IsCurrent = Request.Form["PAns"];
            if (IsCurrent == "Y")
            {
                PAns.Visible = true;
                PYes.Visible = true;
                PNo.Visible = false;
                BindMenuAccessList();
            }
            else
            {
                PAns.Visible = true;
                PYes.Visible = false;
                PNo.Visible = true;
                BindMenuAccessList2();
            }
        }

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protected void UserAdd_Click(object sender, EventArgs e)
    {
        if (MenuAccess.Items.Count > 0)
        {
            for (int i = 0; i < MenuAccess.Items.Count; i++)
            {
                if (MenuAccess.Items[i].Selected)
                {
                    SqlConnection conn1;
                    SqlCommand comm1;
                    string connectionString = ConfigurationManager.ConnectionStrings["DataString"].ConnectionString;
                    conn = new SqlConnection(connectionString);
                    comm = new SqlCommand("INSERT INTO ACC_Menus (LinkID) VALUES (@LinkID)", conn);
                    comm.Parameters.Add("@LinkID", System.Data.SqlDbType.Int);
                    comm.Parameters["@LinkID"].Value = MenuAccess.Items[i].Text;
                    try
                    {
                        conn.Open();
                        comm.ExecuteNonQuery();
                    }
                    finally
                    {
                        conn.Close();
                    }
                }
            }
        }
    }

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Why are you binding menulist on postback?
if (Page.IsPostBack == true)

When I first started I was binding it on page load and it did not work.

It binds fine. When I load the page, the names and values are shows in the Listbox.

yes but when you rebind it on postback the selected values are lost...
so you mush put your code in
if(!Page.IsPostBack){ }

Put what code in this: if(!Page.IsPostBack){ } ? BindMenuAccessList()?

Yes... the code to bind your MenuAccess ListBox control

That worked...however I am getting a different error Invalid Input string. It has to do with this line

comm.Parameters["@LinkID"].Value = MenuAccess.Items[i].Text;

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When I hard code a value like this:
comm.Parameters["@LinkID"].Value = "3";

It works fine.

Are you getting any empty string for the Text?
Try to cast the value to Int32 like:

comm.Parameters["@LinkID"].Value = Convert.ToInt32(MenuAccess.Items[i].Text);

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it is reading the first value and inserting it as many times I selected the values. So I select 5 items and the first value is 12. It is insertring the 12 five times into the table instead of 12, 7, 3, 6, 2

When you debug and check the value on each loop do you see right value being assigned to the LinkID parameter or not?
if not..
Try using the ListItem while looping instead of an Items collection...like shown here: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.listbox.aspx

foreach (ListItem li in ListBox1.Items)
          {
              if (li.Selected == true)
              {
                  msg += "<BR>" + li.Text + " is selected.";
              }
          }

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When I do that the text shows (LinkName) instead of the actual value (Link ID).

Change Password is selected.
List Users is selected.
New User is selected.
Update User is selected.
Delete User is selected.

It should be

12 is selected.
7 is selected.
5 is selected.
4 is selected.
2 is selected.

Its binding right

            MenuAccess.DataValueField = "LinkID";
            MenuAccess.DataTextField = "LinkName";
            MenuAccess.DataBind();
            Menureader.Close();

It works great. Thank you for your help.