Very Strange RPC error

Note: I'm using Photon Unity Networking

When I use my RPC, I'm getting this error: 'ArgumentException: failed to convert parameters' that leads to line 2149 of NetworkingPeer when double clicked. I remember seeing that photon has support for serializing both byte-arrays and shorts and the error log is just a bunch of jargon to me so I'm not sure what's happening.

Here's my code:

 void Start()
 {
 byte[] SendInfo = new byte[]{0,0,0};
 short PosX = 5;
 short PosX = 6;
 photonView.RPC ("SetupCommand", PhotonTargets.All, SendInfo, PosX, PosY);//Tests with debug.log show that this is the line in the code responsible for the error
 }
 
 [RPC] public void SetupCommand (byte[] SendInfo, PosY, PosY)
 {
 //This is never reached
 }

Here's the full errorlog:

ArgumentException: failed to convert parameters System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:192) System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115) NetworkingPeer.ExecuteRPC (ExitGames.Client.Photon.Hashtable rpcData, .PhotonPlayer sender) (at Assets/3rdScripts/Photon Unity Networking/Plugins/PhotonNetwork/NetworkingPeer.cs:2149) NetworkingPeer.RPC (.PhotonView view, System.String methodName, PhotonTargets target, System.Object[] parameters) (at Assets/3rdScripts/Photon Unity Networking/Plugins/PhotonNetwork/NetworkingPeer.cs:2945) PhotonNetwork.RPC (.PhotonView view, System.String methodName, PhotonTargets target, System.Object[] parameters) (at Assets/3rdScripts/Photon Unity Networking/Plugins/PhotonNetwork/PhotonNetwork.cs:2494) PhotonView.RPC (System.String methodName, PhotonTargets target, System.Object[] parameters) (at Assets/3rdScripts/Photon Unity Networking/Plugins/PhotonNetwork/PhotonView.cs:557) GameManager.SendCommand (Int32 ID, Int16 PosX, Int16 PosY) (at Assets/GameManager.cs:101) GameManager.Update () (at Assets/GameManager.cs:164)

and here's the line the error log leads to:

 object result = mInfo.Invoke((object)monob, new object[] { inMethodParameters });