Photon RPC "DestroyRpc" function not found

Hey, recently I added Photon Networking to my game and I am trying to send a Test RPC from my ServerTool to my Client.

The ServerTool code (sending RPC):

 void OnGUI()
 {
     if(GUI.Button(new Rect(0, 0, 100, 40), "Test MSG"))
     {
         GetComponent<PhotonView>().RPC("TestLog", PhotonTargets.All, true);
     }
 }
 
 [RPC]
 public void TestLog(bool test)
 {
     Debug.LogWarning("Test");
 }

The Client (receiving the RPC):

 [RPC]
 void TestLog(bool test)
 {
     Debug.LogWarning("Test");
 }

The Error I get on the Client:

 PhotonView with ID 1 has no method "DestroyRpc" marked with the [RPC](C#) or @RPC(JS) property! Args: Boolean
 UnityEngine.Debug:LogError(Object)
 NetworkingPeer:ExecuteRPC(Hashtable, PhotonPlayer) (at Assets/Photon Unity Networking/Plugins/PhotonNetwork/NetworkingPeer.cs:2005)
 NetworkingPeer:OnEvent(EventData) (at Assets/Photon Unity Networking/Plugins/PhotonNetwork/NetworkingPeer.cs:1643)
 ExitGames.Client.Photon.PeerBase:DeserializeMessageAndCallback(Byte[])
 ExitGames.Client.Photon.EnetPeer:DispatchIncomingCommands()
 ExitGames.Client.Photon.PhotonPeer:DispatchIncomingCommands()
 PhotonHandler:Update() (at Assets/Photon Unity Networking/Plugins/PhotonNetwork/PhotonHandler.cs:76)

The thing that confuses me is that the Error complains about the missing "DestroyRpc" function which isn't even called (by me). The Client-script is attached to the MainCamera which has a PhotonView.

What am I doing wrong? Please help, thank you