VO+SHFT+spacebar Not Working

[Richie Gardenhire]

I'm writing on behalf of a friend of mine who says, when he tries to  
do the VO+SHFT+spacebar command, he gets a click, but nothing  
happens.  I suggested going into the System Preference pane and tab  
down to Keyboard and Mouse tab, and try to adjust so that when he  
issues that command, it should work.  Unfortunately, he said that  
still didn't work.  I know that there are workarounds, but he likes  
using that command.  What adjustments should he make to reactivate the  
VO+SHFT+spacebar command for clicking the mouse?  Thanks.  Richie  
Gardenhire, Anchorage, Alaska.