Hello, just noticed that on my 30D sometimes I cannot change the aperture size with the big dial on back of camera. The shutter speed changes fine with the dial next to the shutter button. The dial works ok when in menus and stuff. Am I being really dumb or is there a problem. I have tried re-attaching the lens (Kit lens) and powering on/off.

Thanks so much...Sitting here wondering what the hell was going on...only had it a few days and suddenly thinking something was wrong lol (At work without manual 
