Klient wcf (400) Bad Request.

Jest programik, usługa systemowa. Programik wysyła requesty do web serwisu. Pierwsze wywołanie nie przechodzi i zwraca 400 kolejne działają prawidłowe. Ktoś ma jakiś pomysł?

System.ServiceModel.ProtocolException: The remote server returned an unexpected response: (400) Bad Request. ---> System.Net.WebException: The remote server returned an error: (400) Bad Request.
at System.Net.HttpWebRequest.GetResponse()
at System.ServiceModel.Channels.HttpChannelFactory`1.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout)
--- End of inner exception stack trace ---

Server stack trace:
at System.ServiceModel.Channels.HttpChannelUtilities.ValidateRequestReplyResponse(HttpWebRequest request, HttpWebResponse response, HttpChannelFactory1 factory, WebException responseException, ChannelBinding channelBinding) at System.ServiceModel.Channels.HttpChannelFactory1.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout)
at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)
at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)

Exception rethrown at [0]:
at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)