Erro ao acessar o webService

public class web {
	public Integer soma(Integer a, Integer b) {
		return (new Integer(a.intValue() + b.intValue()));
	}
}

import java.rmi.RemoteException;
import javax.xml.rpc.ServiceException;
import org.apache.axis.client.Call;
import org.apache.axis.client.Service;

public class Teste {
	
	public static void main(String[] args) {
				
		try {
			
			String url = "http://localhost:8080/axis/web.jws";
			Object param[] = {new Integer(10), new Integer(10)};
			Service s = new Service();
			Call call = (Call) s.createCall();
			call.setTargetEndpointAddress(url);
			call.setOperationName("soma");
			Integer ret = (Integer)call.invoke(param);
			System.out.println("resultado: " + ret);

			
			
		} catch (RemoteException e) {
			System.out.println(e);
		} catch (ServiceException e) {
			System.out.println(e);
		}
	}
}

Integer ret = (Integer)call.invoke(param);

[#text: java.lang.NullPointerException

at java.util.Hashtable.put(Unknown Source)

at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl.setProperty(Unknown Source)

at org.apache.axis.encoding.DeserializationContextImpl.parse(DeserializationContextImpl.java:246)

at org.apache.axis.SOAPPart.getAsSOAPEnvelope(SOAPPart.java:538)

at org.apache.axis.Message.getSOAPEnvelope(Message.java:376)

at org.apache.axis.client.Call.invokeEngine(Call.java:2583)

at org.apache.axis.client.Call.invoke(Call.java:2553)

at org.apache.axis.client.Call.invoke(Call.java:2248)

at org.apache.axis.client.Call.invoke(Call.java:2171)

at org.apache.axis.client.Call.invoke(Call.java:1691)

at teste.Teste.main(Teste.java:41)