Modal Popup Closes

Hi

I have below Aspx. When i select KRA value it should fresh SubKRA dropdown but it closes the Modal. 

    

        

            

                

                    KRA *
                    
                        Select KRA
                    
                
            
            

                

                    Sub KRA *
                    
                        Select Sub KRA
                    
                
            
        
    

protected void Page_Load(object sender, EventArgs e)
{
    try
    {
        if (!Page.IsPostBack)
        {
            BindKRAMaster();
            GetData();
        }
    }
    catch (Exception ex)
    {
        Utility.SaveErrorLog(ex.Message, System.IO.Path.GetFileName(Request.Path), System.Reflection.MethodBase.GetCurrentMethod().Name, hdfEmpNumber.Value);
        ShowMessage("Oops...", ex.Message, "error");
    }
}
private void GetData()
{
    try
    {
        StringBuilder htmlTable = new StringBuilder();

        BALAchievementMeasurement bALAchievementMeasurement = new BALAchievementMeasurement();
        List Result = bALAchievementMeasurement.GetRecordList();

        if (Result != null)
        {
            htmlTable.Append("");

            htmlTable.Append("");
            htmlTable.Append("");

            foreach (var colum in Result)
            {
                String Status = colum.Active == true ? "Active" : "Blocked";
                String modifyAllowed = colum.ModificationAllowed == true ? "Yes" : "No";
                String deleteAllowed = colum.DeleteAllowed == true ? "Yes" : "No";

                htmlTable.Append("");
                htmlTable.Append("");
                htmlTable.Append("");
                htmlTable.Append("");
                htmlTable.Append("");
                htmlTable.Append("");
                htmlTable.Append("");
                //htmlTable.Append("");
                //htmlTable.Append("");
                htmlTable.Append("");
                htmlTable.Append("");

                htmlTable.Append("");
                htmlTable.Append("");
                htmlTable.Append("");

                htmlTable.Append("");
                htmlTable.Append("");

                htmlTable.Append("");
            }
            htmlTable.Append("");
            htmlTable.Append("
Id
KRASetup Id
Sub KRASetup Id
Performance Goal
Payout
Action Plan
Status
Actions
#
1
2
3
4
" + colum.AchievementSetupID + "
" + colum.KRASetupID + "
" + colum.SubKRASetupID + "
" + colum.Performance + "
" + colum.Payout + "
" + colum.ActionPlan + "
" + colum.DeleteAllowed + "
" + colum.ModificationAllowed + "
" + Status + "
" + colum.Active + "
" + colum.KRASetupID + "
" + colum.SubKRASetupID + "
" + colum.DeleteAllowed + "
" + colum.ModificationAllowed + "
");
            PlaceHolderTable.Controls.Add(new Literal { Text = htmlTable.ToString() });
        }
    }
    catch (Exception ex)
    {
        Utility.SaveErrorLog(ex.Message, System.IO.Path.GetFileName(Request.Path), System.Reflection.MethodBase.GetCurrentMethod().Name, hdfEmpNumber.Value);
        ShowMessage("Oops...", ex.Message, "error");
    }
}
private void BindKRAMaster()
{
    try
    {
        BALKRASetup bALKRASetup = new BALKRASetup();
        List Result = bALKRASetup.GetActiveRecordList();
        if (Result != null)
        {
            ddlKRA.DataTextField = "KRASetupID";
            ddlKRA.DataValueField = "KRASetupID";
            ddlKRA.DataSource = Result;
            ddlKRA.DataBind();
            ddlKRA.Items.Insert(0, new ListItem("Select KRASetupID", ""));
        }
    }
    catch (Exception ex)
    {
        Utility.SaveErrorLog(ex.Message, System.IO.Path.GetFileName(Request.Path), System.Reflection.MethodBase.GetCurrentMethod().Name, hdfEmpNumber.Value);
        ShowMessage("Oops...", ex.Message, "error");
    }
}
protected void KRA_Changed(object sender, EventArgs e)
{
    try
    {
        ddlSubKRA.Items.Clear();
        if (ddlKRA.SelectedItem.Value != "")
        {
            Int32 SubKRA = int.Parse(ddlKRA.SelectedItem.Value);
            if (SubKRA > 0)
            {
                BindSubKRA();
            }
        }
    }
    catch (Exception ex)
    {
        Utility.SaveErrorLog(ex.Message, System.IO.Path.GetFileName(Request.Path), System.Reflection.MethodBase.GetCurrentMethod().Name, hdfEmpNumber.Value);
        ShowMessage("Oops...", ex.Message, "error");
    }
}
private void BindSubKRA()
{
    try
    {
        BALSubKRASetup bALSubKRASetup = new BALSubKRASetup();
        List Result = bALSubKRASetup.GetRecordListByKRA(Convert.ToInt32(ddlKRA.SelectedItem.Value));
        if (Result != null)
        {
            ddlSubKRA.DataTextField = "SubKRASetupID";
            ddlSubKRA.DataValueField = "SubKRASetupID";
            ddlSubKRA.DataSource = Result;
            ddlSubKRA.DataBind();
            ddlSubKRA.Items.Insert(0, new ListItem("Select Sub KRA", ""));
        }
    }
    catch (Exception ex)
    {
        Utility.SaveErrorLog(ex.Message, System.IO.Path.GetFileName(Request.Path), System.Reflection.MethodBase.GetCurrentMethod().Name, hdfEmpNumber.Value);
        ShowMessage("Oops...", ex.Message, "error");
    }
}

Thanks