7Soul you're answer is so short that it looks wrong (:
@wp2000 for some (probably good) reasons I didn't have the motivation to investigate, c2 doesn't allow dt to be greater than 0.1s, if your game is slower than 10 fps, dt will then be wrong.
on 60 fps -> dt = 1/60 = 0.017 so after 60 frames of adding dt you get 1 (probably what 7Soul meant)
on 10 fps -> dt = 1/10 = 0.1 after 10 frames you get 1 as well
on 5 fps -> dt = 1/10 = 0.1 after 5 frames you only get 0.5 and that's probably your issue
The work around is to compute your own dt value using the wallclocktime system property.
I made a practical example few days ago: hiddenObjectClock.capx