How to apply a WebCameraTexture to a projector ?

Hi,

I want to apply a WebCameraTexture to a projector so for now I made that :

 renderTexture.mainTexture = webcamTexture;
 
 gameObject.GetComponent<Projector>().material = renderTexture;
 
  webcamTexture.Play();

Where renderTexture is a material.

But I got this message : NullReferenceException: Object reference not set to an instance of an object CameraTexture.Start ().

Any idea ?

Thank you.