Resolved Dragging UI while moving not working right

So, the canvas is in world space as a child of the camera.
The problem is that if I move or rotate the camera the UI goes all over the place, like this:

This is the code as of yet, I'm not sure how to fix it:

Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.EventSystems;
3.  
4. public class Draggable : MonoBehaviour, IDragHandler
5. {
6.     public Camera cam;
7.  
8.     public void OnDrag(PointerEventData data)
9.     {
10.         Vector3 mouseWorld = cam.ScreenToWorldPoint(new Vector3(MouseObject.screenPos.x, MouseObject.screenPos.y, transform.position.z));
11.         mouseWorld.z = transform.position.z;
12.         transform.position = mouseWorld;
13.     }
14. }
15.  

Thanks in advance

 

Solved it, the z part of the cam.ScreenToWorldPoint has to be a fixed number, as it is the distance from the camera