Physics not working...

I apologize if this had been asked before, but I did a search and all the explanations I found as to how to fix it don't seem to be working.

I have a simple pong game with a touch controlled paddle and ball. The ball has "circle" bounds and is set to "bounce" for collision with other objects as well as the world bounds (which are set around the perimeter of the screen. I then set the linear velocity of the ball, and it will bounce around on the screen and interact with the paddle. Ok, so everything runs fine from the both the editor on my PC as well as the one on my Mac. I can even compile it for the simulator and everything still runs fine. However, when I compile it for the iTouch, the ball doesn't go anywhere. The paddle responds to my touch, but the ball just won't move.

I then did a search and found a solution--the [object].setUsesPhysics(true) function. So, I added this code into the "game/gamescripts/game.cs" script file:

function bubbleBall::onLevelLoaded(%this,%scenegraph)
{
   echo("I'm here!!!");
   %this.setUsesPhysics(true);
   %this.setLinearVelocity(80,60);
}

When compiled and run on the device, the "I'm here!!!" text is displayed in the GDB--confirming the function is being executed. However, the ball still won't move. The odd thing about it all is that the ball used to move, but at some point (I guess I inadvertently did something) it stopped.

Any help would be greatly appreciated!