title: NLog throws configuration exception on all aspnet layout renderers
body: <p>I have been working to set up NLog v2 on my ASP.NET MVC 3 application and it has worked very well so far.  (I'm using the package from the offical nuGet repository)  However, when I try to change the log layout to include any of the aspnet-* layout renderers, I get a configuration error.  I've reduced the problem to the following minimum use case:</p>
  
  <p>In the configSections block:</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;section name="nlog" type="NLog.Config.ConfigSectionHandler, NLog"/&gt;
  </code></pre>
  
  <p>The Nlog block:</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" throwExceptions="true"&gt;
  
  &lt;variable name="logDirectory" value="C:\Logs" /&gt;
  &lt;targets&gt;
    &lt;target name="logFile" xsi:type="File" fileName="${logDirectory}\app.log"
        layout="${aspnet-user-identity}" /&gt;
  &lt;/targets&gt;       
  
  &lt;rules&gt;
    &lt;logger name="*" minlevel="Info" writeTo="logfile" /&gt;
  &lt;/rules&gt;
  </code></pre>
  
  <p></p>
  
  <p>If I change layout use any combination of renderers that are not part of the aspnet* family, this works well (I haven't tested every one, but I've looked at quite a few).  The error I get is here:</p>
  
  <pre><code>Configuration Error 
  Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately. 
  
  Parser Error Message: An error occurred creating the configuration section handler for nlog: Exception occurred when loading configuration from C:\..[snip]..\web.config
  
  Source Error: 
  
  
  Line 16: &lt;/configSections&gt;
  Line 17: 
  Line 18:   &lt;nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
  Line 19:     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" throwExceptions="true"&gt;
  Line 20: 
  </code></pre>
  
  <p>I have really no idea what's going on.  I'm not sure what about that renderer causes the configuration to become invalid.  I've been banging around at it most of the day and have gotten nowhere, so I'm hoping someone here can help.</p>
  
  <p>Thank you!</p>