Help on reading the <s:Header> fields from a WCF Service in a Silverlight Client

Question

Hi all. I have a WCF service (.svc) that I am referencing in a SL4 client.

The call looks something like this:

private void Button_Click(object sender, RoutedEventArgs e)
    {
        var client = new SecurityBrokerServiceClient();

        client.AuthenticateUserCompleted += client_AuthenticateUserCompleted;
        client.AuthenticateUserAsync(txtLogin.Text, txtPassword.Password);
    }

 void client_AuthenticateUserCompleted(object sender, AuthenticateUserCompletedEventArgs e)
    {


    }

If I use the WCFTestClient to test the service, I get an XML result like this:

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"&gt;
  <s:Header>
    <SecurityBrokerToken xmlns="SecurityBrokerService">1824</SecurityBrokerToken>
  </s:Header>
  <s:Body>
    <AuthenticateUserResponse xmlns="http://tempuri.org/"&gt;
      <AuthenticateUserResult xmlns:a="http://schemas.datacontract.org/2004/07/SecurityBrokerService" xmlns:i="http://www.w3.org/2001/XMLSchema-instance"&gt;
        <a:EMail>[email protected]</a:EMail>
        <a:Name>name</a:Name>
        <a:UserID>1824</a:UserID>
      </AuthenticateUserResult>
    </AuthenticateUserResponse>
  </s:Body>
</s:Envelope>

But in my Silverlight client, I can't seem to access the s:Header information, only the AuthenticateUserCompletedEventArgs e results.

Anyone got any ideas?

Thanks!