gridview not displayed what's the solution

<asp:Label ID="lbl_selcat" runat="server" Text="Select catalogue:">
       <asp:DropDownList ID="ddl_catalogue" runat="server">
       
      <asp:GridView ID="GridView1" runat="server"  DataKeyNames="id" onrowcancelingedit="GridView1_RowCancelingEdit" 
          onrowdeleting="GridView1_RowDeleting" onrowediting="GridView1_RowEditing" 
          onrowupdating="GridView1_RowUpdating"
       AutoGenerateColumns="False" BorderColor="Black" BorderWidth="2px" 
          HeaderStyle-BackColor="#FF6600" HeaderStyle-BorderStyle="NotSet" 
          HeaderStyle-Font-Bold="True" HeaderStyle-Font-Italic="True" 
          HeaderStyle-Font-Size="Medium" HeaderStyle-Font-Underline="True" 
          HeaderStyle-ForeColor="White">
           <columns>
           
             <asp:BoundField DataField="id" HeaderText="ID" />
               <asp:BoundField DataField="cat_id" HeaderText="cat_id" />
               <asp:BoundField HeaderText="Name" DataField="name" />
               <asp:BoundField DataField="type" HeaderText="Type" />
               <asp:BoundField DataField="price" HeaderText="Price" />
               <asp:ImageField DataImageUrlField="image" HeaderText="IMAGE">
               <controlstyle height="200px" width="200px" />
               
               <asp:BoundField DataField="description" HeaderText="Description" />
               <asp:CommandField ShowEditButton="True" />
               <asp:CommandField ShowDeleteButton="True" />
              </columns>

<HeaderStyle BackColor="#FF6600" Font-Bold="True" Font-Italic="True" Font-Size="Medium" Font-Underline="True" ForeColor="White"></HeaderStyle>

protected void Page_Load(object sender, EventArgs e)
   {
       if (IsPostBack != true)
       {
           ddl_catalogue.DataSource = GetData();
           ddl_catalogue.DataValueField="cat_id";
           ddl_catalogue.DataTextField = "cat_nm";
           ddl_catalogue.DataBind();
           ddl_catalogue.Items.Insert(0, new ListItem("---Select---", "0"));


       }

   }

 protected void ddl_catalogue_SelectedIndexChanged(object sender, EventArgs e)
   {
       SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True");
       SqlCommand cmd = new SqlCommand("select * from cat_detail where cat_id='"+ddl_catalogue.SelectedValue+"'", con);
       con.Open();
       SqlDataReader dr = cmd.ExecuteReader();
       if (dr.HasRows)
       {
         GridView1.DataSource = dr;
         GridView1.DataBind();

       }
               dr.Close();
               con.Close();
   }
   DataTable GetData()
   {
           DataTable dt=new DataTable();
           SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True");
           SqlCommand cmd=new SqlCommand("select * from catalogue",con);
           con.Open();
           SqlDataAdapter sda=new SqlDataAdapter(cmd);
           sda.Fill(dt);
           return dt;
   }