Right in the middle of a shoot yesterday my 580EXII just quit firing. It was working fine, then nothing. Everything seems to be functioning on it except it won't fire. It wasn't over used and I changed to fresh batteries, so those weren't the problem. It was on my camera, 50D, and no shoe cord. Any suggestions? I had this happen to an older 580EX also and just wrote it up as worn out, but this flash is not even a year old yet, granted it gets a lot of use, but I figured it shouldn't die on me yet.

