Not familiar with the product, but I'm guessing it's got a plywood frame, or some kind of timber involved? Sounds to me like wood rubbing against metal or another piece of wood. As a temporary fix, you could take a can of white lithium grease and spray it around liberally, and see if that solves the problem. If you can identify the area that's causing the squeak, a permanent solution would be to place a piece of lightweight fabric, like cotton, between the two surfaces. You could try doing that behind the metal rails for example.