SoapExtension won't execute

I have a SoapExtension which, for now, only writes a log:

public class CatchInputParametersExtension : SoapExtension
{
    public override object GetInitializer(Type serviceType)
    {
        return null;
    }

    public override object GetInitializer(LogicalMethodInfo methodInfo, SoapExtensionAttribute attribute)
    {
        return null;
    }

    public override void Initialize(object initializer)
    {
        //nothing to do
    }

    public override void ProcessMessage(SoapMessage message)
    {
        Logger.Log("++++++++ Before Everything +++++++ " + message.ToString(), LogLevel.Info);

        switch (message.Stage)
        {
            case SoapMessageStage.BeforeSerialize:
                Logger.Log("++++++++ Before Serialize +++++++ " + message.ToString(), LogLevel.Info);
                break;
            case SoapMessageStage.AfterSerialize:
                Logger.Log("++++++++ After Serialize +++++++ " + message.ToString(), LogLevel.Info);
                break;
            case SoapMessageStage.BeforeDeserialize:
                Logger.Log("++++++++ Before Deserialize +++++++ " + message.ToString(), LogLevel.Info);
                break;
            case SoapMessageStage.AfterDeserialize:
                Logger.Log("++++++++ After Deserialize +++++++ " + message.ToString(), LogLevel.Info);
                break;
            default:
                throw new Exception("invalid stage");
        }

    }
}

I tried registering it with both web.config file

<webServices>
  <soapExtensionTypes>
    <add type="WebAdminServices.SoapExtensions.CatchInputParametersExtension,WebAdminServices" priority="1" group="Low"/>
  </soapExtensionTypes>
</webServices>

and SoapExtensionAttribute

[AttributeUsage(AttributeTargets.Method)]
public class CatchInputParametersAttribute : SoapExtensionAttribute
{

    private int priority;

    public override Type ExtensionType
    {
        get { return typeof(CatchInputParametersExtension); }
    }

    public override int Priority
    {
        get { return priority; }
        set { priority = value; }
    }

}

which is registered by

    [WebMethod(Description = "Test1")]
    [CatchInputParametersAttribute(Priority=1)]
    public string Test1(int a, int b, int c)
    {
        // do stuff

        return stuff;
    }

but none of them seems to work, the log file never shows those ++++++ lines. Any hints, please?

Solution

Ok, this is a little bit silly. The SoapExtension is working fine, but I was calling the web method through the automatically generated HTTP Post, thinking that the SoapExtension was executing underneath. But it wasn't.

So for trigger its execution you need to call it through a client using a SOAP request directly. For that purpose I used WebServiceStudio, which analyzes a given .wsdl and lets you make SOAP requests.

More info: Using SOAP Extensions in ASP.NET.