Slight disassembly bug witha GHK AKM
 

Hi guys, just received this splendid replica. It's weird but I'm not able to remove the top cover when pressing the rear button. I had no problem with my old CYMA AKM but on this one, it doesn't even move at all. It's nothing that need brain to remove so I don't understand why it doesn't move, even after pressing with all my strenght on the rear button. Any advices? Thanks guys :)