dont get why my query is returning a null

My problem is related to when I want to Delete a Item off a Order,

I just dont get why it is returning a null value it should just delete the item.

protected void gvRevOrder_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
    Int64 ID = new Int64();
    ID = (Int64)e.Keys["ProductID"];

    using (DatabaseCourseWorkEntities  context = new DatabaseCourseWorkEntities())
    {
        CWInvoiceItem item = (from p in context.CWInvoiceItems 
                              where p.ProductID == ID 
          开发者_运维技巧                    select p).SingleOrDefault();

        context.CWInvoiceItems.DeleteObject(item);
        context.SaveChanges();
    }

below i have put a link of the thing i am trying to delete and as you can see the ProductID = 38 and the Variable ID also has 38 any ideas?

I've tried all sorts such as FirsOrDefault and such.

1. Check that context.CWInvoiceItems contains ANY data
2. Check that the context points to the correct data source