Modal Popup Closes

Question

Hi

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

<div class="form-horizontal">
    <div class="modal-body">
        <div class="row">
            <div class="col-lg-6 col-md-6 col-sm-12">
                <div class="form-group">
                    <label>KRA</label>&nbsp;<span style="color: red">*</span>
                    <asp:DropDownList ID="ddlKRA" class="form-control" runat="server" required="true" AutoPostBack="true"  OnSelectedIndexChanged="KRA_Changed">
                        <asp:ListItem Value="">Select KRA</asp:ListItem>
                    </asp:DropDownList>
                </div>
            </div>
            <div class="col-lg-6 col-md-6 col-sm-12">
                <div class="form-group">
                    <label>Sub KRA</label>&nbsp;<span style="color: red">*</span>
                    <asp:DropDownList ID="ddlSubKRA" class="form-control" runat="server" required="true">
                        <asp:ListItem Value="">Select Sub KRA</asp:ListItem>
                    </asp:DropDownList>
                </div>
            </div>
        </div>
    </div>
</div>

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<AchievementMeasurementSetup> Result = bALAchievementMeasurement.GetRecordList();

        if (Result != null)
        {
            htmlTable.Append("<table class='table table-bordered table-hover datatable-highlight' id='tbldata'>");

            htmlTable.Append("<thead><tr><th style='display:none'>Id</th><th>KRASetup Id</th><th>Sub KRASetup Id</th><th>Performance Goal</th><th>Payout</th><th>Action Plan</th><th>Status</th><th class='text-center nosort'>Actions</th><th style='display:none'>#</th><th style='display:none'>1</th><th style='display:none'>2</th><th style='display:none'>3</th><th style='display:none'>4</th></tr></thead>");
            htmlTable.Append("<tbody>");

            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("<tr>");
                htmlTable.Append("<td style='display:none'>" + colum.AchievementSetupID + "</td>");
                htmlTable.Append("<td>" + colum.KRASetupID + "</td>");
                htmlTable.Append("<td>" + colum.SubKRASetupID + "</td>");
                htmlTable.Append("<td>" + colum.Performance + "</td>");
                htmlTable.Append("<td>" + colum.Payout + "</td>");
                htmlTable.Append("<td>" + colum.ActionPlan + "</td>");
                //htmlTable.Append("<td>" + colum.DeleteAllowed + "</td>");
                //htmlTable.Append("<td>" + colum.ModificationAllowed + "</td>");
                htmlTable.Append("<td>" + Status + "</td>");
                htmlTable.Append("<td class='text-center'><a id='btnEdit' style='cursor:pointer;' class='list-icons-item text-primary-600' data-toggle='modal' data-backdrop='static' data-keyboard='false' data-target='#modal_form_horizontal' onclick='BindData(this);'><i class='icon-pencil7 mr-1'></i></a></td>");

                htmlTable.Append("<td style='display:none'>" + colum.Active + "</td>");
                htmlTable.Append("<td style='display:none'>" + colum.KRASetupID + "</td>");
                htmlTable.Append("<td style='display:none'>" + colum.SubKRASetupID + "</td>");

                htmlTable.Append("<td style='display:none'>" + colum.DeleteAllowed + "</td>");
                htmlTable.Append("<td style='display:none'>" + colum.ModificationAllowed + "</td>");

                htmlTable.Append("</tr>");
            }
            htmlTable.Append("</tbody>");
            htmlTable.Append("</table>");
            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<KRASetupMaster> 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<SubKRASetupMaster> 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