SOAP exception : axis2ns2:selectionFailure

im getting an unknown exception when doing a request to a webservice:

axis2ns2:selectionFailure

Anyone know what the problem is ?

Edit: detailed error:

{"Message":"axis2ns5:selectionFailure","StackTrace":"   at System.Web.Services.Protocols.SoapHttpC开发者_JAVA百科lientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)\r\n   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)\r\n   

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This problem occurs when there is an error with the xml namespace.