corner-radius vs border-radius

I wouldn't mind pitching in to help here as I would love to be able to use this for a project I am working on. One of the things I came across that is not rendering properly in CSS is "border-radius". In the code it looks for "corner-radius" but that is not even valid CSS. Was there a reason for that?

Hi. I have nothing to do with this project but I think it might be because this predates border-radius. You might as well ask about the gradients.