binding menu control with Database in asp.net

Hi i have 3 tables these are products table, catagory table, and sub catagory table. using these 3 tables i need to bind menu control with sql server database. in this when i click product name i have to display the catagoies and sub catagories and i have to display the content of catagories and sub catagories while clicking those sub catagories.

i am using this code

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using System.IO;

public partial class construction_materials : System.Web.UI.Page
{
string str = System.Configuration.ConfigurationManager.AppSettings["ConnectionString"].ToString();

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{

PopulateMenu();

}
}
DataSet GetMenuData()
{
SqlConnection con = new SqlConnection(str);
SqlDataAdapter dadCats = new SqlDataAdapter("SELECT catid, catname,productid FROM tbl_productcatagory where productid=1", con);
SqlDataAdapter dadProducts = new SqlDataAdapter("SELECT subcatid, catid, subcatagoryname FROM tbl_productsubcatagory ", con);
DataSet dst = new DataSet();
dadCats.Fill(dst, "tbl_productcatagory");
dadProducts.Fill(dst, "tbl_productsubcatagory");
dst.Relations.Add("Children",
dst.Tables["tbl_productcatagory"].Columns["catid"],
dst.Tables["tbl_productsubcatagory"].Columns["catid"]);
return dst;
}


public void PopulateMenu()
{
DataSet dst = GetMenuData();
foreach (DataRow masterRow in dst.Tables["tbl_productcatagory"].Rows)
{
MenuItem masterItem = new MenuItem((string)masterRow["catname"]);
Menu1.Items.Add(masterItem);
foreach (DataRow childRow in masterRow.GetChildRows("Children"))
{
MenuItem childItem = new MenuItem((string)childRow["subcatagoryname"], "", "", ("~/default.aspx?catid=" + (masterRow["catid"].ToString()) + "&subcatid=" + (childRow["subcatid"].ToString())), "_parent");
masterItem.ChildItems.Add(childItem);
}
}

}
}

But i am getting this error.

This constraint cannot be enabled as not all values have corresponding parent values.

can u please help me....

Tags: C# (C# 2.0), ASP.NET