Why am I ineligible for a tax rebate?

My wife and I were married last year and filed jointly for '07. Her parents claimed her as a dependant (I don't think they were supposed to - she is 20 and not a full-time student), but I am not anyone's dependant. According to the IRS' website, I do not qualify for a rebate because someone else claimed me as their dependant...is this because her parents claimed her, or is there some other "funny business" going on? Thanks!