Changing material on an object multiple times

Hi all,

My current project revolves around a light / dark theme, where dark tiles spread from the outside of a grid towards the center. I'm having trouble with setting different materials to the tile objects. The following code is on the tile prefab;

     void Awake(){
         this.gameObject.renderer.material = this.lightTex;
     }

The following is called from a grid manager which tells the tile to turn to the dark material. This works for this purpose.

 public void changeDark(bool turnDark){
         if(turnDark == true){
             if(this.gameObject.renderer.material = this.lightTex){
             isLight = false;
             isDark = true;
             this.gameObject.renderer.material = this.dark;
             }

The following is called from the player which is using the player position to create a temporary list of targets and then sending a message to each of the targets to call this.

 public void TargettedTile(){
         if(this.gameObject.renderer.material = this.dark){
             this.gameObject.renderer.material = this.lightTex;
             gameObject.renderer.
             Debug.Log ("Was Dark now light" + gameObject.renderer.material.name);
             
         }
     }

At the moment the tiles will turn black but will not turn back to light, any ideas?

Thanks

Renoclaf