Well, I know in Michigan it's really difficult to get in-state tuition. In fact, I have a friend who followed all of the rules to the letter to get residency for the University of Michigan as an undergrad. He worked in Michigan for over a year, he registered to vote, changed his licence, paid state income taxes, got utilities in his name -- did everything. And he still was denied with no reason given.
He appealed though and he was given residency on appeal. And I've heard of more than just my friend having a similar experience at the U of Mich. It's like they just deny everybody who's even borderline and see if they appeal.
My point is that if you aren't given residency and you think you've fufilled the requirements, you should appeal.