Update Belt during Motion Analysis

Hello all,

I have a system of pulleys and a belt following them.  Whenever I move a pulley and rebuild, the belt automatically updates it's length and position.  I am trying to determine how to monitor, and ultimately graph, a change in belt length as a pulley moves through it's range of motion.  I ran the motion analysis but as the pulley moves, the belt does not update it's position/length.  Can anyone shed some light on this situation?

I am using Solidworks Premium 2010 SP4

Thanks.

-Jason

SolidworksMotion Studies