On Click of CommandField(Edit Button) issue

Hi,
In my gridview, I have taken a CommandField for the Edit functionality and I have set it as an Image. But the problem is that when I give " ControlStyle-Width="15", i cant see Update and Cancel Button.
Please help.
<asp:CommandField ShowEditButton="True" ItemStyle-Width="15" ButtonType="Image" EditImageUrl="~/images/edit.png" ControlStyle-Width="15" ControlStyle-Height="15" />