GUI Variable Declaration problem

 var OptionState : boolean  = false;    
     var Option : Rect  = new Rect(bwidth2,bheight2 + margin,bwidth,bheight); //holds actual button rect coordinates
     var initialPosition : Rect = new Rect(bwidth2,bheight2 + margin,bwidth,bheight); //holds starting rect coordinates
     var activePosition : Rect = new Rect(-bwidth,bheight2 + margin,bwidth,bheight); //holds ending rect coordinates
     Option.width = bwidth2;
     //==========================================
     FPSCamera = transform.Find("Main Camera");
 
 
 
 
     MainArrow = gameObject.Find("Guide");
     
     function OnGUI(){
     
     if(GUI.Button(Option,"Option!"))
         {
          
          if(OptionState){
                 iTween.ValueTo(gameObject,iTween.Hash("from",Option,"to",initialPosition,"onupdate","MoveButton","easetype","easeinoutback","ignoretimescale",true));    
             }else{
                 iTween.ValueTo(gameObject,iTween.Hash("from",Option,"to",activePosition,"onupdate","MoveButton","easetype","easeinoutback","ignoretimescale",true));
             }
             OptionState = !OptionState;
         }
     
     }

I want to auto Size and auto Place my Button to Center at the same time if I click it, it will animate. but the button always setting up to 0,0,0,0. Please Help me Good Guys.