"One-Way" Platform

Hi Im tring to get this code to work but It won't do it evry time I go and jump up (under it) it still collides with the bottom of my scene object.

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

	%template.friendlyName = "Platform Object";
	%template.behaviorType = "Platform";
	%template.description  = "Platform object";

	%template.addBehaviorField(OneWay, "One-Way Platform", bool, 0);
}

function PlatformBehavior::onAddToScene(%this, %scenegraph)
{
	%this.owner.setCollisionActive(0,1);
	%this.owner.setCollisionCallback(0);

	%this.owner.setCollisionPhysics(0,0);
	%this.owner.isGround = true;

	%this.owner.isOneWay = %this.OneWay;
}