When I try to update a record, I get:

Specified argument was out of the range of valid values. Parameter name:
index

Exception Details: System.ArgumentOutOfRangeException: Specified argument
was out of the range of valid values. Parameter name: index

Source Error:

Line 133: SqlCommand updCommand = new SqlCommand();
Line 134: updCommand.Connection = conn;
Line 135: updCommand.CommandText = "UPDATE GEM.customers SET name = '"
Line 136: + ((TextBox)e.Item.Cells[6].Controls[0]).Text
Line 137: + "', address = '"

and the UPDATE line is selected. Can someone tell me what the error means?

Thanks,

Antonio