RED BAR IN TIME LINE OF MOTION STUDY

   hi All,

i'm new to motion studies, and i have a question about the RED (not solved) bar in the time line... how do you determine what is causing the problem?  things were working pretty good, but now i have a RED bar in the timeline and  the sim is not performing as it should.  however, i cannot find what is causing the conflict.  when i scroll thru all the parts and mates and motors in the Feature manager tree, there are no RED marks.  how do you determine what is the problem?

thanks,

Tom

SolidworksMotion Studies