[PV3D] 'MaterialObject3D: transformUV() material.bitmap not found!'

[Souji]

Hi there,
I was recently trying to import some collada models from 3d studio max into flash. Everything looks fine, but I have some kind of error which rather shouldn't appear:

'MaterialObject3D: transformUV() material.bitmap not found!'

I've found some answers by googling it, but I'm not sure.
How should properly deal with this problem?
Here is my code

package 
{
    import flash.display.Sprite;
    import flash.events.Event;
    
    import org.papervision3d.cameras.Camera3D;
    import org.papervision3d.objects.parsers.Collada;
    import org.papervision3d.render.BasicRenderEngine;
    import org.papervision3d.scenes.Scene3D;
    import org.papervision3d.view.Viewport3D;
    
    import org.papervision3d.materials.*
    import org.papervision3d.materials.utils.*
    import org.papervision3d.objects.parsers.Collada;
    
    [SWF(width="640", height="480", frameRate="30", backgroundColor="#000000")]

    public class Kwadrat extends Sprite
    {
        private var scene:Scene3D;
        private var vp:Viewport3D;
        private var cam:Camera3D;
        private var bre:BasicRenderEngine;
        private var collada:Collada;
        
        public function Kwadrat()
        {
            setupPV3D();
            addCollada();
            addEventListener(Event.ENTER_FRAME, loop);
        }
        
        private function setupPV3D():void
        {
            scene = new Scene3D();
            cam = new Camera3D();
            cam.zoom =0.5;
            cam.focus =100;
            //cam.z = 10;
            //cam.x = 10;
            //cam.y = 10;
            vp = new Viewport3D();
            bre = new BasicRenderEngine();
            addChild(vp);
        }   
        
        private function addCollada():void
        {
            var mat:BitmapFileMaterial= new BitmapFileMaterial("kwadrat.png");
            var mp:MaterialsList = new MaterialsList();
            mp.addMaterial(mat, "kwadrat");
            collada = new Collada("kwadrat.DAE", mp);
            scene.addChild(collada);
        }   
        
        private function loop(e:Event):void
        {
            //collada.rotationY += 2;
            //collada.rotationX += 1;
            bre.renderScene(scene, cam, vp);
        }
    }
}

Can anyone help?