SD Card IP Core Compatibility (DE1)

It's been a rather long time since I posted this but I managed to solve this problem. Firstly this was a problem with my top level entity and pin assignments, which I fixed. Secondly only certain SD cards work. I managed to get a Transcend 2GB microSD card working but the rest of my cards, which are unbranded, did not (probably because of incompatible speed class). It would probably be beneficial if Altera provided a specification of which types of cards work since I can't find any in the relevant documentation.