Applying interactive MovieMaterial to sprite3D will cause error

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Create a Sprite3D instance and apply MovieMaterial to it like following:

var one:Sprite3D=new Sprite3D();
var mc:Sprite=new Sprite();
mc.graphics.beginFill(0xff0000);
mc.drawRect(0,0,100,100);
mc.graphics.endFill();
var mat:MovieMaterial=new MovieMaterial(mc);

mat.interactive=true;

one.material=mat;
scene.addSprite(one);

2. Run the code
3. Move mouse over the instance

What is the expected output? What do you see instead?
When mouse over the Sprite3D object, error is given as following:

[Fault] exception, information=TypeError: Error #1009: Cannot access a property 
or method of a null object reference.
pointing to: MovieMaterial.as line 74 
x = event.uv.u*_renderBitmap.width;

What version of the product are you using? On what operating system?
Away3d 3.6.0, FlashDevelop

Please provide any additional information below.

Original issue reported on code.google.com by EEpErY...@gmail.com on 10 Apr 2011 at 10:03