that's not helpful, because although it limits the UPPER limit of the frame rate, it does nothing to help those with slower systems.
for example you set your sync rate to 50. people with fast computers can experience your game exactly as you intended, but imagine someone who'se computer can only run your program at 30fps. that's still a goot frame rate, but they will be experiencing a game running in "slow motion", because everything will me moving at 3/5 speed. that's why sync rate isn't a good idea- you need to use a timer() based system to make sure that even at 10fps, your game objects all move at the appropriate speed.
sorry for the long tangent, and unfortunately as I mentioned above, I have no idea how yo solve your problem
Go Go Gadget DBPRO!
