title: Error using Logback Marker in FileAppender
body: <p>I have started exploring Logback option for our application. One of the requirement is to create a separate log file for log entries that have a specific "Marker".</p>
  
  <p>Below is the logback.xml file that i am using and the error I am getting. The examples on the logback website shows the usage of SMTPAppender but I would like to use FileAppender instead. Is this possible? If not, what other option do i have? </p>
  
  <pre><code>&lt;property name="USER_HOME" value="c:/temp" /&gt;
  
  &lt;appender name="AUDIT_FILE" class="ch.qos.logback.core.FileAppender"&gt;        
      &lt;evaluator class="ch.qos.logback.classic.boolex.OnMarkerEvaluator"&gt;
          &lt;marker&gt;APPEND_SYSLOG&lt;/marker&gt;
      &lt;/evaluator&gt;
      &lt;file&gt;${USER_HOME}/mw_syslog.log&lt;/file&gt;        
      &lt;encoder&gt;
          &lt;pattern&gt;%date %level [%thread] %logger{10} [%file:%line] %msg%n&lt;/pattern&gt;
      &lt;/encoder&gt;
  &lt;/appender&gt;
  
  &lt;root level="debug"&gt;
      &lt;appender-ref ref="AUDIT_FILE" /&gt;
  &lt;/root&gt;
  
  
      12:07:01,515 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Found resource [logback.xml] at [file:/C:/JavaProjects/LogbackWeb/target/LogbackWeb-1.0-SNAPSHOT/WEB-INF/classes/logback.xml]
      12:07:02,013 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - debug attribute not set
      12:07:02,134 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [ch.qos.logback.core.FileAppender]
      12:07:02,176 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [AUDIT_FILE]
      12:07:02,286 |-ERROR in ch.qos.logback.core.joran.spi.Interpreter@43:76 - no applicable action for [evaluator], current pattern is [[configuration][appender][evaluator]]
      12:07:02,286 |-ERROR in ch.qos.logback.core.joran.spi.Interpreter@44:21 - no applicable action for [marker], current pattern is [[configuration][appender][evaluator][marker]]
      12:07:02,310 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property
      12:07:02,828 |-INFO in ch.qos.logback.core.FileAppender[AUDIT_FILE] - File property is set to [c:/temp/mw_syslog.log]
      12:07:02,836 |-INFO in ch.qos.logback.classic.joran.action.RootLoggerAction - Setting level of ROOT logger to DEBUG
      12:07:02,836 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [AUDIT_FILE] to Logger[ROOT]
      12:07:02,842 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - End of configuration.
      12:07:02,855 |-INFO in ch.qos.logback.classic.joran.JoranConfigurator@3ad1a015 - Registering current configuration as safe fallback point
  </code></pre>