For anyone who just rolled through PoR on easy mode in order to beat the game quickly and pump their characters full of bonus experience, however, Radiant Dawn will laugh at you and then slap you in the face for good measure. See, easy mode files don't transfer over to Radiant Dawn because (as you'll know if you've played the game), the word "easy" isn't in its vocabulary. Even if you try to transfer a normal or hard mode file while having any easy mode PoR files saved somewhere else on your card, Radiant Dawn will have none of that.
Christian from The Tanooki decided to contact Nintendo on the issue, and it seems that Nintendo will have a fix ready by mid-December. In order to get your disc repaired (or possibly get a completely new disc), you have to contact Nintendo about the issue, give them your name, address, and phone number, and then send your disc to them when prompted.
So, what lesson have we learned from all this? Well, that Fire Emblem is for badasses only, of course.