overloading webmethods

Hi all,
does anyone knows if I can overload webmethod in C#, I would like to do this:
[WebMethod]
public string GetParcelByAddress(string streetName, string streetNumber)
{
return;
}

[WebMethod]
public string GetParcelByAddress(string streetName)
{
return;
}

but, I am getting error messge:

Both System.String GetParcelByAddress(System.String) and System.String GetParcelByAddress(System.String, System.String) use the message name 'GetParcelByAddress'. Use the MessageName property of the WebMethod custom attribute to specify unique message names for the methods.

<b>WebMethodAttribute.MessageName Property</b>

You must use this property in order to get polymorphism.

The name used for the XML Web service method in the data passed to and returned from an XML Web service method.

[AttributeUsage(AttributeTargets.Method)]
public string MessageName {get; set;}


Property Value
The name used for the XML Web service method in the data passed to and from an XML Web service method. The default is the name of the XML Web service method.


The MessageName property can be used to alias method or property names. The most common use of the MessageName property will be to uniquely identify polymorphic methods. By default, MessageName is set to the name of the XML Web service method. Therefore, if an XML Web service contains two or more XML Web service methods with the same name, you can uniquely identify the individual Web Service methods by setting the MessageName to a name unique within the XML Web service, without changing the name of the actual method name in code.

When data is passed to an XML Web service it is sent in a request and when it is returned it is sent in a response. Within the request and response, the name used for the XML Web service method is its MessageName property.

The message name associated with an XML Web service method must be unique within the XML Web service.

If a new XML Web serivce method with the same name but different parameters is added after clients are calling the original method, a different message name should be specified for the new method but the original message name should be left as is to ensure compatability with existing clients.

In the example below, MessageName is used to disambiguate the two Add methods.

<%@ WebService Language="C#" Class="Calculator" %>

using System;
using System.Web.Services;

public class Calculator : WebService {
// The MessageName property defaults to Add for this XML
Web service method.
[WebMethod]
public int Add(int i, int j) {
return i + j;
}
[WebMethod(MessageName="Add2")]
public int Add(int i, int j, int k) {
return i + j + k;
}
}

hope this help. Szilard