createClassObject returning null value when creating dynamic components.

createClassObject returning null value when creating dynamic components.

I am using the following code

var __reg2 = new Object();
__reg2.label = _label;
__reg2._width = _w;
__reg2._height = _h;
__reg2._x = this.width / 2 - _w / 2;
__reg2._y = this.height / 2 - _h / 2;
__reg2._alpha = 0;

this.launch_button = this.mc.createClassObject(controls.PixtorieButton, "launch_button", this.mc.getNextHighestDepth(), __reg2);

this.mc is a movieclip which has the correct value during runtime but when i use createClassObject() with it its always returning null value.

I have the component dragged into my library.

Also the code fails even when i am using mx.controls.Button instead of controls.PixtorieButton .

Any help will be greatly appreciated

Thanks in advance