I recentlly aquired a d50 from my mother in law. She quit using it because the on camera flash doesn't fire. I took it to a local camera shop and they checked every setting to see if we somehow turned it off, and they couldn't find anything wrong with it. Has anyone else had this problem? It isn't too big of a deal because I just ordered a sb-600 for it and my d40, but i would like to fix it if possible. Thanks for any input.