Sharepoint 2010 Event receiver not firing for subsite

I have an event receiver (WebAdding and WebProvisioned) which works just fine for sites created off the root of the site collection. However, subsites (for example, teamsites created within other areas) do not trigger the code at all.

Does anyone have any idea as to why?

using System;
using System.Security.Permissions;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Security;
using Microsoft.SharePoint.Utilities;
using Microsoft.SharePoint.Workflow;
using System.Text;

namespace TestEventReceiver.EventReceiver1
{
  /// <summary>
  /// Web Events
  /// </summary>
  public class EventReceiver1 : SPWebEventReceiver
  {
    /// <summary>
    /// A site is being provisioned.
    /// </summary>
    public override void WebAdding(SPWebEventProperties properties)
    {
      base.WebAdding(properties);

      using (SPWeb web = properties.Web)
      { 
        StringBuilder output = new StringBuilder();
        output.AppendFormat("Web Adding");
        output.AppendFormat("<br>Web title: {0}",web.Title);
        SendMyEmail(web, "SendItToMe@MyTestAddress.com", "Web Adding", output.ToString());
      }
    }

    /// <summary>
    /// A site was provisioned.
    /// </summary>
    public override void WebProvisioned(SPWebEventProperties properties)
    {
      base.WebProvisioned(properties);
      using (SPWeb web = properties.Web)
      {
        StringBuilder output = new StringBuilder();
        output.AppendFormat("Web Provisioned");
        output.AppendFormat("<br>Web title: {0}", web.Title);
        SendMyEmail(web, "SendItToMe@MyTestAddress.com", "Web Provisioned", output.ToString());
      }
    }

    private void SendMyEmail(SPWeb Web, String toAddress, String subject, String message)
    {
      bool appendHtmlTag = false;
      bool htmlEncode = true;
      SPSecurity.RunWithElevatedPrivileges(delegate()
      {
        SPUtility.SendEmail(Web, appendHtmlTag, htmlEncode, toAddress, subject, message);
      });

    }

  }
}

Thanks in advance,
Matt