error while consuming axis web service

[tikoti tikotev]

Hi all!

I have created a very simple axis2 webservice but while trying to call it from a .net client I get the following error:
"The ServiceClass object does not implement the required method in the following form: OMElement add(OMElement e)"

The code of the webservice is as follows:

package addition;

public class add {
public int add(int a, int b) {
return a+b;
}
}

and the META-INF/services.xml as follows:

<?xml version="1.0" encoding="UTF-8"?>

<service name="arithmetic">
<description>addition program</description>
<messageReceivers>

<messageReceiver mep="http://www.w3.org/2004/wsdl/in-out"
class="org.apache.axis2.rpc.receivers.RPCMessageReceiver"/>
</messageReceivers>

<parameter name="ServiceClass" locked="false">addition.add</parameter>
</service>

However, when I try to call it from a .net client (I attach the code anyway) I get the mentioned error

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using arithmeticReference;

public partial class _Default : System.Web.UI.Page
{
    private arithmeticPortTypeClient proxy;
    protected void Page_Load(object sender, EventArgs e)
    {
        proxy = new arithmeticPortTypeClient("arithmeticHttpSoap12Endpoint");
    }

    protected void OnBtnClicked(object sender, System.EventArgs e)
    {
        string n1 = num1.Text;
        string n2 = num2.Text;

        int res = proxy.add(4, 7);
    }
}

I would appreciate if anybody could give me any advice

Thank you all!