Heater Core replacement

I'm in the process of replacing my heater core and I've taken everything off inside the car to remove the access cover but the damn thing won't budge free. I've taken out 7 screws (4 passenger side, 3 driver side) that look like they hold the cover on but even without screws the thing won't come off. Am I missing something or should the thing be off by now, I've come to close to be stopped by a piece of plastic.