org.apache.axis2.AxisFault: java.lang.NoSuchMethodError: Exception org.apache.ws.security.WSPasswordCallback.getIdentifer()Ljava/lang/String;

when i test my web service client I get the following exception:

org.apache.axis2.AxisFault: java.lang.NoSuchMethodError: org.apache.ws.security.WSPasswordCallback.getIdentifer()Ljava/lang/String;
    at org.apache.axis2.util.Utils.getInboundFaultFromMessageContext(Utils.java:531)
    at org.apache.axis2.description.OutInAxisOperationClient.handleResponse(OutInAxisOperation.java:375)
    at org.apache.axis2.description.OutInAxisOperationClient.send(OutInAxisOperation.java:421)
    at org.apache.axis2.description.OutInAxisOperationClient.executeImpl(OutInAxisOperation.java:229)

and I don't know what may be the reason. Here is my Password callback handler class 


publicclassPWCBHandlerimplementsCallbackHandler{publicvoidhandle(Callback[]callbacks)throwsIOException,UnsupportedCallbackException{


try{for(inti =0;i <callbacks.length;i++)


 {    WSPasswordCallbackpwcb =(WSPasswordCallback)callbacks[i];

        Stringid =pwcb.getIdentifier();

        if("bob".equals(id))

         {

                pwcb.setPassword("bobPW");

         }


}


}catch(Exceptionex){ex.printStackTrace();}}