Why my c# script doesn't work?

Now I have been trying to edit the "MouseLook" script on my own. Now I want to disable "mouselook" when i press "i". Question is why it works sometimes and other times dont? I mean sometimes it looks away when i move the mouse even i am pretty sure that I pressed "i". using UnityEngine; using System.Collections;

 public class MouseLook : 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;
 
     
     public  bool Inventoryenabled = false;
     float rotationY = 0F;
 
     void Update ()
     {
 
         if(Input.GetKey("i")){
             Inventoryenabled = !Inventoryenabled;
                         
             
         }
         
         
         if(!Inventoryenabled){
         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 (GetComponent<Rigidbody>())
             GetComponent<Rigidbody>().freezeRotation = true;
     }
 }