Rocks'n'Diamonds

I collected already all the diamonds (more than the amount needed) and the Exit door won't open. I serached other locals and it doesn't see it have a hidden passage. Why is this happening?

You know those square thingies that float in the air and you push around? Those are actually Sokoban objects.

Yes, I remember, so that squares you walk on is where you put them. Alrighty, thanks.