make sure that your feet are centered on the rail. if you are off center you will slide off, i had that same problem. try to make sure your coming strait at the rail that helps too.
originally posted by chris_64_impala : why do u need a fat ski? huh fatty? yeah thats right u like the chocoalte
I had the same problem as you. The trick is waiting for a split second off the jump before you turn 90 degrees. This prevents you from carving off the lip and for some reason seems to lock you onto the rail. Give it a shot - once you get used to switch on its just as easy as straight.