Well, it was kinda strange, but I solved it already. In the door_open() function, there was a line of code:
if((event_type == EVENT_CLICK) && (vec_dist(player, my) <= 100))
So I left out the vec_dist part, and then everything worked just fine. I think it had something to do with the player, but I'm not too sure... Anyway, It's solved, so I'm a happy guy. ^_^
