User Interface

I've been experimenting with the SL user interface. So far I have got some of the buttons made. I decided to try the radio buttons (those round circle single-choice buttons) and not having any luck getting those to change out with my custom graphic. Is the user interface limited to what you can change?

Attached it a screenshot of the button graphics I made. I even specified my own radio button graphics but as you can see they do not update. Even when I clear cache and relog.