JQuery WCF .net 4 Rest 405 Method Not Allowed Trivial

Question

I keep getting a 405 Method not allowed. The script is hosted on same port as server, using IIS.

<script>
function auth() {
   var str= '{"Password":"Password","Username":"Username"}';
   $.ajax({
      type: "POST",
      contentType: "application/json; charset=utf-8",
      url: "http://127.0.0.1:8080/auth/authenticate",
      data: str,
      success: function(data) { alert(data) },
      dataType: "json"
   });
}
</script>

Web Service

[WebInvoke(UriTemplate = "auth/authenticate", Method = "POST")]
public AuthenticationReturn Authenticate(AuthenticationCredentials credentials)
{
    try
    {            
        AuthenticationReturn ad = new AuthenticationReturn();
        DateTime now = DateTime.Now;
        ad.AuthorizationToken = "some_string_" + now.Ticks.ToString();
        ad.UserIdentifier = "some_identifier_" + now.Ticks.ToString();
        ad.Expiration = now.AddYears(1);
        return ad;
     }
     catch (InvalidOperationException ioe)
     {
        throw new WebFaultException<InvalidOperationException>(ioe, System.Net.HttpStatusCode.BadRequest);
     }
 }