You can't have an else if without an if for starters.

Also, preloading is done with LoadLevelAsync(). What your doing is loading the level which will freeze the current level.

So you probably want to do something more like:

function Start () {
     if(animation)  //is there and animation component on this object
          animation.Play("Loading");

     var async : AsyncOperation = Application.LoadLevelAsync (1);
     yield async; //Wait while the level is loading in the background

     Application.LoadLevel(1);
}