NGUI- lerping widget on Y Axis only working in one direction

So I have a widget i want to lerp between two positions as its toggeled. one is at -48 and the other is 0. The idea is when its not being used it will move off-screen.

It lerps off screen perfectly but when i try to move it back (when its turned on) it just snaps to position. I must be missing something.

//Warning Code Dump immenant// using UnityEngine; using System.Collections;

 public class toggleMessageBox : MonoBehaviour {
     public Transform messageBoxPos;
     public float showY=0f;
     public float hideY=-48f;
     public bool showMessageBox=false;
     public float lerpY=0;
     public float prevLerpY=0;
     public float counter=0;
     public float y=0;
     // Use this for initialization
     void Start () 
     {
         messageBoxPos = GameObject.Find ("MessageBox").GetComponent<Transform> () as Transform;
     }
     
     // Update is called once per frame
     void Update () 
     {
         y = messageBoxPos.position.y;
         //update lerpY if needed
         if (showMessageBox) 
         {
             lerpY = showY;
         } 
         else 
         {
             lerpY = hideY;
         }
 
         //check to see if it changed
         if (lerpY != prevLerpY) 
         {
             counter=0;
             prevLerpY=lerpY;
         }
 
         //get the new position
         Vector3 temporaryPosition = messageBoxPos.position;
         temporaryPosition = Vector3.Lerp (temporaryPosition, new Vector3 (temporaryPosition.x, lerpY, temporaryPosition.z), counter);
         //update the counter
         counter += Time.deltaTime;
         if (counter > 1) 
         {
             counter = 1;
         }
         //finally update the position
         messageBoxPos.localPosition = temporaryPosition;
     }
 }