I've enabled tracing on a small "hello world" web service, and it is simply
not working. No file is created, no tracing occurs.

What are some common reasons this might occur?  I've already checked
filesystem permissions, IIS permissions...

I've manually modified my web.config, and also used the WSE configuration
tool to do it instead.  Nothing works.  Tracing on another webservice on the
same machine functions properly.

<configuration>
 <configSections>
   <section name="microsoft.web.services2"
type="Microsoft.Web.Services2.Configuration.WebServicesConfiguration,
Microsoft.Web.Services2, Version=2.0.0.0, Culture=neutral,
PublicKeyToken=31bf3856ad364e35" />
 </configSections>

.........

   <webServices>
     <soapExtensionTypes>
       <add type="Microsoft.Web.Services2.WebServicesExtension,
Microsoft.Web.Services2, Version=2.0.0.0, Culture=neutral,
PublicKeyToken=31bf3856ad364e35" priority="1" group="0" />
     </soapExtensionTypes>
   </webServices>
 </system.web>
 <microsoft.web.services2>
   <diagnostics>
     <trace enabled="true" input="InputTrace.webinfo"
output="OutputTrace.webinfo" />
   </diagnostics>
 </microsoft.web.services2>