Mouselook when holding lmb or rmb problem

Hello guys I am trying to create a script so that the mouselook only works when i hold the lmb or rmb. So far I can't make it to work . Thanks in advance!

Here is the code

using UnityEngine;
using System.Collections;


[AddComponentMenu("Camera-Control/Mouse Look Restricted")]
public class MouseLookRestricted : MonoBehaviour {

public enum RotationAxes { MouseXAndY = 0, MouseX = 1, MouseY = 2 }
public RotationAxes axes = RotationAxes.MouseXAndY;
public float sensitivityX = 15F;
public float sensitivityY = 15F;

public float minimumX = -360F;
public float maximumX = 360F;

public float minimumY = -60F;
public float maximumY = 60F;

float rotationY = 0F;

void Update ()
{
//only do mouse look if right mouse button is down
if (Input.GetMouseButton (1)|| Input.GetKey ("left shift") || Input.GetKey ("right shift")
|| Input.GetButton ("Horizontal") || Input.GetButton ("Vertical"))

{
transform.localEulerAngles = new Vector3 (-rotationY, transform.localEulerAngles.y, 0);
}





if (axes == RotationAxes.MouseXAndY)
{
float rotationX = transform.localEulerAngles.y + Input.GetAxis("Mouse X") * sensitivityX;

rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);

transform.localEulerAngles = new Vector3(-rotationY, rotationX, 0);
}
else if (axes == RotationAxes.MouseX)
{
transform.Rotate(0, Input.GetAxis("Mouse X") * sensitivityX, 0);
}
else
{
rotationY += Input.GetAxis("Mouse Y") * sensitivityY;
rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);

transform.localEulerAngles = new Vector3(-rotationY, transform.localEulerAngles.y, 0);
}
}

void Start ()
{
// Make the rigid body not change rotation
if (rigidbody)
rigidbody.freezeRotation = true;
}
}