Im pretty sure I know what ur talking about hold on...... That wall that blocks the laser, you have to raise it via a switch in the room somewhere. It'll go up then u move the box under the wall. NOT ON THE STEP, under the wall. then activate the laser. Viola
, oh and by the way... watch your step. and mind the spinning blade thing in the room below. lol
And if u cant do that then you have glitched somehow. Just remeber, you CAN NOT move the box up on the step. just right next to it. and make sure the box is against the wall. Good luck, and get ya some Vortigons!