Problems in Max,..

Currently ive got my rig walking upto a box at an angle and i want him to push this box along slightly and then for it finally to give and flip on its edge, which isnt straight on to him. The picture best explains it as im having hella problems setting up the link relationship properly between the boxs pivot and this extra pivot. Currently pivot 1 can work fine but soon as i rotate pivot 2 the box goes skewif in a really wierd way. Im going to go about it a different way but Id definately like to know how to get by this in future.