Webcamtexture not showing on a SpriteRenderer

I've been trying to get a WebCamTexture onto a sprite-renderer, and I've looked through other questions, but none of them have solved the problem I've been having.

The material, once applied to the sprite-renderer, just shows up as a purple sheet. I am attempting to apply the WebCamTexture to a white sprite as a background.

     public GameObject testObj;
 
     private WebCamTexture m_texture = null;
 
     void Start ()
     {
         Application.RequestUserAuthorization (UserAuthorization.WebCam);
 
         m_texture = new WebCamTexture ("Remote Back Camera");
 
         m_texture.Play ();
 
         gameObject.GetComponent<SpriteRenderer>().material.mainTexture = m_texture;
         gameObject.GetComponent<SpriteRenderer> ().material.renderQueue = 3001;
     }
 
     private void Update ()
     {
         if (null != m_texture &&
             m_texture.didUpdateThisFrame) {
             gameObject.GetComponent<SpriteRenderer>().material.SetTexture = m_texture;
         }
     }

The camera is working, and I can get it working with a GUITexture, but I need it to be behind several sprites, and in front of others, so a Sprite-Renderer seems like the best way to do that.

Any help would be greatly appreciated, thanks!