3rd person Controller problem

hi people,
i have some problems with my script for a 3rd person controller…
i made a biped in 3d max and i have a few animation to it… idle,walk,jump,and throw…
how should i script it so that my char can walk and stop the walking animation wen no key is pressed… currently i am using this scripts and it doesnt seem to work…pls help me out… what am i doing wrong…

/// This script moves the character controller forward
/// and sideways based on the arrow keys.
/// It also jumps when pressing space.
/// Make sure to attach a character controller to the same game object.
/// It is recommended that you make only one call to Move or SimpleMove per frame.
var speed = 6.0;
var jumpSpeed = 8.0;
var gravity = 20.0;

private var moveDirection = Vector3.zero;

function Start ()
{
// We are in full control here - don’t let any other animations play when we start
// animation.Stop();
// By default loop all animations
animation.wrapMode = WrapMode.Loop;
}
function Update() {

var controller : CharacterController = GetComponent(CharacterController);
if (controller.isGrounded){
// We are grounded, so recalculate
// move direction directly from axes
moveDirection = Vector3(Input.GetAxis(“Horizontal”), 0,
Input.GetAxis(“Vertical”));
moveDirection = transform.TransformDirection(moveDirection);
moveDirection *= speed;

if (Input.GetAxis(“Vertical”) > 0)
{
animation.CrossFade(“walk”);
}

if (Input.GetButton (“Jump”)) {
moveDirection.y = jumpSpeed;
animation.CrossFade(“jump”);

if(Input.GetButton (“Fire1”))
{
animation.Play(“throw”);
}
}
}
// Create an animation cycle for when the character is turning on the spot
if(Input.GetAxis(“Horizontal”) !Input.GetAxis(“Vertical”))
{
animation.CrossFade(“walk”);
}

transform.eulerAngles.y += Input.GetAxis(“Horizontal”);

// Apply gravity
moveDirection.y -= gravity * Time.deltaTime;

// Move the controller
controller.Move(moveDirection * Time.deltaTime);
}

I dont think the standard biped in 3DsMax gets imported into Unity when using the fbx format(if that is the format you’re using), and have you ever tried to see if your character plays the animations without the script?