Forms Data Controls :: GridView Delete Command Fires Error When Using Template Fields Inside

I have visual 2010 with net 3.5 web app. I was implementing EntityFramework in my project and added a gridview to a entity source control. It worked ok, with select, update, and delete buttons enabled on the grid. But then, i needed to add a template field bound to a Foreign table, so my users select value from a list instead of writing the code. After that, my app fires error when i delete. I tried everything, inclue dakeyNames, write code on my RowDeleting, RowDeleted, RowCommand, but error persists.

Now, i can delete the row, but it then i get the error Object reference not set to an instance of an object If i implemente delete code on RowCommand i get the error: Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.