Getting response error!!

Hy everyone,
i am new to photon and i don't know completely how it operates still learning. i am having a problem, when ever i try to use login or register on my local server it just won't let me go in to the game or let me register as new user. the error is once i pressed signIN ....... and in my server i am getting DEngine.PhotonFX.Common.PhotonApplication [(null)] - There is an error in XML document (0, 0). this ....... as well as in sign in i am gettin.....

ResponseReceived, OperationCode = SignIn, ReturnCode = InvalidParams, DebugMsg =
UnityEngine.Debug:Log(Object)
LoginController:OnResponse(OperationResponse) (at Assets/Scripts/Network/Controller/LoginController.cs:78)
DEngine.Unity.Photon.PhotonManager:OnOperationResponse(OperationResponse)
ExitGames.Client.Photon.PeerBase:DeserializeMessageAndCallback(Byte[]) (at c:/Dev/photon-sdk-dotnet/PhotonDotNet/PeerBase.cs:676)
ExitGames.Client.Photon.TPeer:DispatchIncomingCommands() (at c:/Dev/photon-sdk-dotnet/PhotonDotNet/TPeer.cs:337)
ExitGames.Client.Photon.PhotonPeer:DispatchIncomingCommands() (at c:/Dev/photon-sdk-dotnet/PhotonDotNet/PhotonPeer.cs:1118)
ExitGames.Client.Photon.PhotonPeer:Service() (at c:/Dev/photon-sdk-dotnet/PhotonDotNet/PhotonPeer.cs:1031)
DEngine.Unity.Photon.Connected:OnUpdate()
DEngine.Unity.Photon.PhotonManager:Update()