Radio problem

Hello all

I tried to fit my pioneer screen in my car and there was nothing no power no lights no nothing so I put the old one back in incase it was the screen but the same nothing at all. I think I should have a earth a 12v perminate feed and a 12v ignition. I've got the earth and ignition feed but no perminate feed. Look in the haynes book and it says that both perminate and ignition feeds come from the same fuse number 42 but that's not blown does anyone have any ideas as what it can be as I'm puzzled :(.

Ta

Chris