problem in WCF service

Getting Error Msg:

No connection could be made because the target machine actively refused it 127.0.0.1:3877

[SocketException (0x274d): No connection could be made because the target machine actively refused it 127.0.0.1:3877]
   System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress) +225
   System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception) +279

[WebException: Unable to connect to the remote server]
   System.Net.HttpWebRequest.GetRequestStream(TransportContext& context) +6022589
   System.Net.HttpWebRequest.GetRequestStream() +13
   System.ServiceModel.Channels.WebRequestHttpOutput.GetOutputStream() +59