[Chimera-users] distance measurement

Hello, I have been using Chimera for some months but suddenly my distance measurement is not working. I pick one atom and then shift-double pick the other atom, the hand shows, it blinks a couple times but no distance menu pops up. Any idea what could be wrong?! I just uninstalled and reinstalled the chimera software again, still the same trouble. [I use a laptop whose mouse works great (except when I need to move the molecules, then I use a real mouse instead of the laptop's finger mouse)]. Any help is greatly appreciated. Thank you for your time. Farhana