system down

///controls playersMovement including mouse event triggers

if (!isObject(PlayerMovementBehavior))
{
%template = new BehaviorTemplate(PlayerMovementBehavior);

%template.friendlyName = "PlayerMovement";
%template.behaviorType = "Input";
%template.description = "controls player movement";


%template.addBehaviorField(xVelocity, "The speed at which the object will move horizontally (world units per second)", float, 5.0);
%template.addBehaviorField(yVelocity, "The speed at which the object will move vertically (world units per second)", float, 5.0);
%template.addBehaviorField(acceleration, "Forward acceleration", float, 10);
%template.addBehaviorField(damping, "Amount to damp movement", float, 5);


}
Hi, I just wrote this script but it has crashed my game. Im not sure why? Anyone?
A quick explanation would do me wonders.

function PlayerMovementBehavior::onBehaviorAdd(%this)
{
   %this.owner.setUseMouseEvents(true);
}
   
function PlayerMovementBehavior::onMouseDown(%this, %worldPos)
{
   %position = %this.owner.position;
   if (%this.moveToPosition)
      %position = %worldPos;
   
   %this.object.Player(%position);
   %this.owner.linearVelocity = %this.xVelocity SPC %this.yVelocity;
 }