Alignment of a set of points to Worldl coordinate system

Hi

I am trying to align a set of points to the world coordinate system by minimising the volume of the bounding box.  However whenever I try to run the Galapagos optimiser, it seems to get stuck on a solution with the xy rotation angle of about 27 degrees.  The optimum is when this angle is 30 degrees.  Despite leaving the optimisation to run for a long time, it never seems to find this angle. 

Can anyone help with this problem?

Many thanks

William