Why does the cube continue moving upward after I tell it to move down afterward?

 public var RemoteIP : String = "127.0.0.1"; //127.0.0.1 signifies a local host (if testing locally
 public var SendToPort : int = 9000; //the port you will be sending from
 public var ListenerPort : int = 8050; //the port you will be listening on
 public var controller : Transform;
 //public var gameReceiver = "Cube"; //the tag of the object on stage that you want to manipulate
 private var handler : Osc;
 public var speed: float;
 public var go: GameObject;
 public var height: int = 0;
 //VARIABLES YOU WANT TO BE ANIMATED
 public var yHeight = new Vector3(0,0,0); //the rotation around the y axis
  
 public function Start ()
 {
     //Initializes on start up to listen for messages
     //make sure this game object has both UDPPackIO and OSC script attached
  
     var udp : UDPPacketIO = GetComponent("UDPPacketIO");
     udp.init(RemoteIP, SendToPort, ListenerPort);
     handler = GetComponent("Osc");
     handler.init(udp);
     handler.SetAllMessageHandler(AllMessageHandler);
  
 }
 Debug.Log("Running");
  
 function Update () {
     var step = speed * Time.deltaTime;
     go.transform.Translate(yHeight, Space.World);
 }
  
 //These functions are called when messages are received
 //Access values via: oscMessage.Values[0], oscMessage.Values[1], etc
  
 public function AllMessageHandler(oscMessage: OscMessage){
  
  
     var msgString = Osc.OscMessageToString(oscMessage); //the message and value combined
     var msgAddress = oscMessage.Address; //the message parameters
     var msgValue = oscMessage.Values[0]; //the message value
     //Debug.Log(msgString); //log the message and values coming from OSC
  
     //FUNCTIONS YOU WANT CALLED WHEN A SPECIFIC MESSAGE IS RECEIVED
     switch (msgAddress){
         case "/attention": 
             Rotate(msgValue);
             break;
         default:
             break;
     }
  
 }
  
  
     //FUNCTIONS CALLED BY MATCHING A SPECIFIC MESSAGE IN THE ALLMESSAGEHANDLER FUNCTION
     public function Rotate(msgValue) : void //rotate the cube around its axis
      {
          height = msgValue/10;
          yHeight = new Vector3(0,height,0);
     }