ASP .NET AJAX Error "Sys.WebForms.PageRequestManagerServerErrorException"

Hello. I receive the folowing error and it seems to have something to do with AJAX.

Sys.WebForms.PageRequestManagerServerErrorException: An unknown error occured while processing the request on the server. The status code retirned by the server was: 500.

Here is the code used on the page. It is really simple and the page works fine if i run it in Visual Studio. As soon as i try to access it through the web i get the error above.

Protected Sub ImageButton1_Click(ByVal sender As Object, ByVal e As System.Web.UI.ImageClickEventArgs)
lblError.Text = ""
        If Page.IsValid = False Then
            Exit Sub
        End If

        Session("Advisor ID") = txtUID.Text
        Session("Advisor Pass") = txtPWD.Text
        Dim dv As DataView = CType(dsLogin.Select(DataSourceSelectArguments.Empty), DataView)

        If dv.Count >= 1 Then
            lblError.Text = "Success......"
            Response.Redirect("Main.aspx")
        Else
            lblError.Text = "Incorrect ID or password. Please reenter and try again . . ."
        End If
End SubStart Free Trial