Scaled GUI

I have a GUI Texture, when I click on it a GUI Button should appear. It all worked well until I put the "scaled code". I found the scaling part on some other question.

How can I make it work? Here's my code.

 private bool displayMusic = false;
 public GUITexture myTexture;
 private Vector3 scale;
 int originalWidth = 640;
 int originalHeight = 400;


 void OnGUI() 
 {
     scale.x = Screen.width/originalWidth; // calculate hor scale
     scale.y = Screen.height/originalHeight; // calculate vert scale
     scale.z = 1;
     Matrix4x4 svMat = GUI.matrix;
     GUI.matrix = Matrix4x4.TRS(Vector3.zero, Quaternion.identity, scale);

     if (Input.GetMouseButton (0) && myTexture.HitTest (Input.mousePosition)) 
     {
         displayMusic=true;                    
     }

     if (displayMusic) 
     { 
         if (AudioListener.volume != 0 && GUI.Button (new Rect(1005,130,135,30), "Sound effects: ON"))
         {
             AudioListener.volume = 0;
             displayMusic=false;
         }
         else 

         if (AudioListener.volume == 0  && GUI.Button (new Rect(1005,130,135,30), "Sound effects: OFF"))
         {
             AudioListener.volume = 100;
             displayMusic=false;
         }

     }
     GUI.matrix = svMat; 
 
 }

}