linq with store procedure using 3 tier

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ASP.NET

LINQ

i work linq with store procure and 3 tier archtecure,
but i have a problem,

I use store procdure like:

ALTER PROCEDURE [dbo].[SP_Category_Get]
(
             @id int=0

)
As
SET NOCOUNT ON
if(@id=0)
Begin
         Select * From tbl_admin_category


End

else
Begin
 Select * From tbl_admin_category
 where
  id= @id

  End
SET NOCOUNT OFF

When i use this procedure direct at code behind:
Then it will be very easy like:

LinqConnectionDataContext li = new LinqConnectionDataContext();
       var v = li.SP_Category_Get(0);

       gd_cat.DataSource = v;
       gd_cat.DataBind();

Now the Problem is:
when i call this store procure at BLL then i need to define every coloumn name which i use at display page, so my code is very lengthy,
so i want that if there are any method for removing this problem:

Code On BLL is:

public IEnumerable<tbl_admin_category> GetCategoryDetails(int id)
    {

        LinqConnectionDataContext li = new LinqConnectionDataContext();
        var v = li.SP_Category_Get(id);

        return (from c in v
                select new tbl_admin_category()
                {
                    id = c.id,
                    category = c.category,
                    category_img = c.category_img
                }
               ).ToList();


    } 

and then at Aspx.cs Page:

adminBal obj = new adminBal();

       var v = obj.GetCategoryDetails(0);
       gd_cat.DataSource = v;
       gd_cat.DataBind();

so i want that,
1. just like first code(when i call Direct SP at aspx.cs page,and i don't need to define coloum name)
2. i dont want to define coloum name at BLL;



And If I try at BLL like This:
Then it also produce Error:

public IEnumerable<tbl_admin_category> GetCategoryDetails(int id)
   {


       var v = li.SP_Category_Get(id);

       return v;


   }

Error is:
Cannot implicitly convert type 'System.Data.Linq.ISingleResult' to 'System.Collections.Generic.IEnumerable<tbl_admin_category>'. An explicit conversion exists (are you missing a cast?)