Migration problems with serial numbers

I have just migrated to a new iMac with Lion from my older iMac running Snow leopard. After a variety of problems with the wifi migrating, I ended up using a firewire cable, and migrated my applications. This morning I tried to open Logic for the first time, and I was asked to enter my serial number, which I eventually found, but when I entered it it said it was invalid. I have tried all the different ways of typing it in- capitals/no capitals, spaces/no spaces- but it says it is invalidd. I thought migration was supposed to prevent these problems. Have I missed something out- do I need to deauthorise the other version? Currently pulling hair out, so all help would be greatly appreciated!