找不到类型或命名空间名称“MyPetshopDataContext”

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 ProductShow : System.Web.UI.Page
  {
  MyPetshopDataContext db = new MyPetShopDataContext();
  protected void Page_Load(object sender, EventArgs e)
  {
  if (!IsPostBack)
  {
  var categories = from c in db.Category
  select new
  {
  c.CategoryId
  c.Name
  };
  foreach (var category in categories )
  {
  ddlCategory.Items.Add(new ListItem (category .Name.ToString(),category .CategoryId.ToString()));
  }
  }
  }
  protected void dllCartegory_SelectedIndexChanged(object sender, EventArgs e)
  {
  Bind();
  }
  protected void Bind()
  {
  int categoryId = int Parse(ddlCategory.SelectrdValue);
  var products = from p in db.Product
  where p.CategoryId == categoryId select p;
  gvProduct .DateSource = products ;
  gvProduct.DataBind ();
  }
  protected void gvProduct_PageIndexChanging(object sender, GridViewPageEventArgs e)
  {
  gvProduct.PageIndex = e.NewPageIndex;
  Bind();
  }
  }



编译器错误消息: CS0246: 找不到类型或命名空间名称“MyPetshopDataContext”(是否缺少 using 指令或程序集引用?)
MyPetshopDataContext db = new MyPetShopDataContext();

请问该怎么改啊

MyPetshopDataContext这个是在哪个空间，你得用头上using XXXXXX