How to use Datakeys with sql server?

Hey All, i'm trying to make my gridview is Editable, i used a sourse code in the internet but i had a problem update and delete methods can't recognize this statement int UserID = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Values[0].ToString()); maybe because i'm using sql server not DataSourse this is the error Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index ..thanks all