Flare3D Collision Issue

package {
    import flare.basic.*;
    import flare.collisions.*;
    import flare.core.*;
    import flare.primitives.*;
    import flare.system.*;
    import flare.utils.*;
    import flash.display.*;
    import flash.events.*;
    import flash.geom.*;

    public class Main extends Sprite {
        private var _scene:Scene3D;
        private var hero:Pivot3D;
        private var heroCollision:SphereCollision;
        private var _level:Pivot3D;

        public function Main():void {
            if (stage) init();
            else addEventListener(Event.ADDED_TO_STAGE, init);
        }

        private function init(e:Event = null):void {
            removeEventListener(Event.ADDED_TO_STAGE, init);
            _scene = new Viewer3D(this);
            _level = _scene.addChildFromFile("assets/test.f3d");

            _scene.addEventListener(Scene3D.COMPLETE_EVENT, onSceneComplete);
        }

        private function onSceneComplete(e:Event):void {
            _scene.removeEventListener(Scene3D.COMPLETE_EVENT, onSceneComplete);
            var cube:Pivot3D = _level.addChild(new Cube("Collision", 50, 50, 50));
            cube.setPosition( -50, 0, 200);
            _createHero();
            _createCamera();
            _scene.addEventListener(Scene3D.UPDATE_EVENT, onSceneUpdate);
        }

        private function _createCamera():void {
            _scene.camera = new Camera3D( "myOwnCamera" );
            _scene.camera.setPosition( 0, 1000, 0 );
            _scene.camera.lookAt(hero.x, hero.y, hero.z);
            _scene.camera.fieldOfView = 60;
        }

        private function _createHero():void {
            var pos:Point = new Point(0, 215);
            var rad:Number = 5;
            hero = _scene.addChild(new Sphere("hero", rad));
            hero.x = pos.x;
            hero.z = pos.y;
            var offset:Vector3D = new Vector3D(0, 0, 0);
            heroCollision = new SphereCollision(hero, rad, offset);
            heroCollision.addCollisionWith(_level, true);
            heroCollision.reset();

            var sphere:Pivot3D = new Sphere("", rad);
            sphere.setPosition(offset.x, offset.y, offset.z);
            hero.addChild(sphere);
        }

        private function onSceneUpdate(e:Event):void {
            var speed:Number = 1;
            if ( Input3D.keyDown( Input3D.UP ) ) hero.translateZ( speed );
            if ( Input3D.keyDown( Input3D.DOWN ) ) hero.translateZ( -speed );
            if ( Input3D.keyDown( Input3D.LEFT ) ) hero.translateX( -speed );
            if ( Input3D.keyDown( Input3D.RIGHT ) ) hero.translateX( speed );

            trace(heroCollision.slider());

            Pivot3DUtils.setPositionWithReference( _scene.camera, 0, 50, 0, hero );
        }

    }

}