Null reference exception on Screenpointtoray (Multiplayer)

Hey all. In my multiplayer game of Hunter vs Hunted the hunted team have to complete objectives. I set up the following script for this…

void Update () {

        if (Input.GetButtonDown("Fire2")){

            NetworkViewID viewID = Network.AllocateViewID();

            networkView.RPC("RaycastObjective",RPCMode.AllBuffered, viewID);

        }

    }

    [RPC]

    void RaycastObjective(NetworkViewID viewID){

        RaycastHit ObjectiveHit = new RaycastHit();

        Ray objRay = Camera.main.ScreenPointToRay(Input.mousePosition);

        if (Physics.Raycast(objRay, out ObjectiveHit, 400))

        {

          if (ObjectiveHit.transform.name == "IDCard")

            {

            currentobjective = 1;

            Debug.Log("Hit Keycard!");  

            Destroy(IDCard);

            }

                if (ObjectiveHit.transform.name == "Generator")

            {

                if (currentobjective == 1)

                {

                    

                Debug.Log("Generator Activated!");

                currentobjective = 2;


                }


            }
  
        }

The problem is that when the Hunter team spawns they get this error…

NullReferenceException
UnityEngine.Camera.ScreenPointToRay (Vector3 position) (at C:/BuildAgent/work/ea95e74f6e5f192d/Runtime/ExportGenerated/Editor/UnityEngineCamera.cs:379)
Obj_Sketchup.RaycastObjective (NetworkViewID viewID) (at Assets/Scripts/MapScripts/Obj_Sketchup.cs:50)
UnityEngine.NetworkView:RPC(String, RPCMode, Object[])
Obj_Sketchup:Update() (at Assets/Scripts/MapScripts/Obj_Sketchup.cs:32)

From what this error says it means that the lines responsible for the error are…

networkView.RPC("RaycastObjective",RPCMode.AllBuffered, viewID);

and…

Ray objRay = Camera.main.ScreenPointToRay(Input.mousePosition);

I can’t for the life of me work out why I would be getting a null reference exception error? I have all cameras tagged properly and it seems odd that only one team are getting the error. What would you suggest for a work around?

This was fixed! I had to use Network.Destroy on the team that have to complete the objectives. This can be closed now.