problem in not showing data of backend(MSSQL)

using System;
using System.Collections;
using System.Configuration;
using System.Data;
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;

public partial class ProductSubCategory : System.Web.UI.Page
{
    Cls_FF c1 = new Cls_FF();
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            filldl_subcategory();
        }
    }
    public void filldl_subcategory()
    {
        DataList2.DataSource = c1.selectDS("select * from ProSubCategory WHERE ProductId='" + Session["Pro_id"] + "'");
        DataList2.DataBind();
    }

    protected void DataList2_ItemCommand(object source, DataListCommandEventArgs e)
    {
        if (e.CommandName == "details")
        {
            string _subcatid;
            _subcatid = ((Label)DataList2.Items[e.Item.ItemIndex].FindControl("lbl_subid")).Text;
            Session.Add("subcatid", _subcatid);
            Response.Redirect("ProductDetail.aspx");

        }
    }
}

<%@ Page Title="" Language="C#" MasterPageFile="~/UserMasterPage.master" AutoEventWireup="true" CodeFile="ProductSubCategory.aspx.cs" Inherits="ProductSubCategory" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
    <style type="text/css">

        .style6
        {
            width: 100%;
        }
        .style12
        {
            width: 100%;
            height: 144px;
        }
        .style13
        {
            width: 100%;
            height: 93px;
        }
        .style14
        {
            width: 100%;
            height: 49px;
        }
        .style18
        {
            width: 100%;
            height: 30px;
        }
    </style>

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    <table align="center" cellpadding="5" cellspacing="0" class="style6">
        <tr>
            <td align="center" class="style18">
                <asp:Label ID="Label3" runat="server" Font-Bold="True" Font-Size="Large" 
                    ForeColor="#663300" Text="Product  Details">
            </td>
        </tr>
        <tr>
            <td align="left">
                <asp:DataList ID="DataList2" runat="server" 
                    onitemcommand="DataList2_ItemCommand" RepeatColumns="2">
                    
                        <table align="center" cellpadding="5" cellspacing="0" class="style6">
                            <tr>
                                <td>
                                    <table align="center" cellpadding="5" cellspacing="0" class="style6">
                                        <tr>
                                            <td align="center" class="style9">
                                                <asp:ImageButton ID="ImageButton2" runat="server" CommandName="Details" 
                                                    Height="112px" ImageUrl='<%# Eval("Image") %>' PostBackUrl="~/GemsDetails.aspx" 
                                                    Width="137px" />
                                            </td>
                                            <td align="left">
                                                <table align="center" cellpadding="5" cellspacing="0" class="style6">
                                                    <tr>
                                                        <td align="center">
                                                            <asp:Label ID="Label4" runat="server" Font-Bold="True" Font-Names="Vani" 
                                                                ForeColor="#FF9900" Text='<%# Eval("SubCategoryName") %>'>