Main Camera GetComponent doesn't work for a script?

Hey guys, im working with Photon Unity Networking and im having trouble setting the camera to the right player. at the moment I am getting an error when I am trying to use Camera.main.GetComponent. The problem is that GetComponent is not recognising the User script as a compnent at all. However it works with other components in Camera.main. Here is the line of code:

 void OnJoinedRoom()
     {
         
         GameObject player = PhotonNetwork.Instantiate ("Character", Vector3.zero, Quaternion.identity, 0);
 
         Camera.main.GetComponent<User> ().target = player.transform;
         
     }