I can't solve the puzzle in the room with laser..how can i put the blu plate into the place to open the upper door?..i get over there but i can't transport it..how can i do??

I did it with a bit of fiddling. Pull out the hidden wall. Hit the lever to switch the laser. Jump up and grab the rope, head up to the top of the screen. grab the key, jump up so that the key lands on the rope. Double jump up so your walking on top of the rope, pick up your key and try balancing ck across the rope, thats how I did it.... Good Luck!

You don't really need to acces the upper area, it's just if you need some alchemic material or a save break.