YEah - try your Apple ID and Pass first. I had the same problem. Had an Apple ID account and Pass plus a .me acct and Pass. Took me quite some time to figure out what was going on - but finally got it figured out. Took a lot of trial and error, try all of your ID names + Password combinations.
ITs a bit strange - the password I use for iTunes with my Apple ID is different from the password I use with iCLoud and damn near eveything else. Yet same Apple ID. Somewhere along the way - you may have switched your password for your current ID, but for whatever reason, it may not have "switched" in all facets.
SO - in conclusiuon - in case I lost you - which i lost myself, I tend to ramble - Try every password/ID combination.