Enemy moving sideways

I have been making a game with enemies that follow and attack you when you get so close to them. I just imported a model from Blender3D when I give it a character controller and the AI script and everything it will follow and attack me, but for some reason it moves sideways. I can't figure out why this is.

 var distance;
 var target : Transform;    
 var lookAtDistance = 15.0;
 var chaseRange = 15.00;
 var attackRange = 1.5;
 var moveSpeed = 5.0;
 var Damping = 6.0;
 var Controller : CharacterController;
 var Gravity : float = 20.0;
 private var MoveDirection : Vector3 = Vector3.zero;
 var AttackRepeatTime = 1;
 private var AttackTime : float;
 var TheDamage = 20;
 
 function Start()
 {
     AttackTime = Time.time;
 } 
 function Update () 
 {
 distance = Vector3.Distance(target.position, transform.position);
  
  if(distance < lookAtDistance)
  {
      lookAt ();
  }   
  if(distance < attackRange)
  {
      attack();
  }
  else
  {
       if(distance < chaseRange)
  {
     chase ();
  }
  }
  }
  
  
 function lookAt ()
 {
  var rotation = Quaternion.LookRotation(target.position - transform.position);
  transform.rotation = Quaternion.Slerp(transform.rotation, rotation, Time.deltaTime * Damping);
 }
  
 function chase ()
 {
   
   moveDirection = transform.forward;
   moveDirection *= moveSpeed;
   
   moveDirection.y -= Gravity * Time.deltaTime;
   Controller.Move(moveDirection * Time.deltaTime);
 }
 
 function attack ()
 {
     if(Time.time > AttackTime)
     {
         target.SendMessage("PlayerHit", TheDamage, SendMessageOptions.DontRequireReceiver);
         AttackTime = Time.time + AttackRepeatTime;
     }
 }