Trying to use coroutines in order to use Mathf.Lerp, Lerp instantly jumps values

What am I doing wrong?

  function scalePlayer(scaleTo : float, timeUp : float, timeDown : float) {
         StopCoroutine("scaleTo");
         StopCoroutine("scaleBack");
         StartCoroutine(scaleTo(scaleTo, timeUp));
         yield WaitForSeconds(timeUp);
         StartCoroutine(scaleBack(scaleTo, timeDown));
     }
     function scaleTo(scaleTo : float, timeUp : float) {
         player.transform.localScale = new Vector3(Mathf.Lerp(objectScale[0], scaleTo, Time.deltaTime/timeUp), Mathf.Lerp(objectScale[1], scaleTo, Time.deltaTime/timeUp), 0);
         yield;
     }
     function scaleBack(scaleTo : float, timeDown : float) {
         player.transform.localScale = new Vector3(Mathf.Lerp(scaleTo, objectScale[0], Time.deltaTime/timeDown), Mathf.Lerp(scaleTo, objectScale[1], Time.deltaTime/timeDown), 0);
         yield;    
     }