Well why are you clicking the wrong button? It's because the radio's aren't visually distinctive enough, isn't it? Your eyes don't quite catch which one is which because they get lost in the clutter.
For me, it's more of a mouse pointer-targeting issue: I know which widget I want to click on, but they're spaced pretty closely together, and once in twenty attempts I miss it. I know which one is which, but every so often I'm off the mark by thirty pixels or so.