title: CheckEventLog Command Issue with NSclient
body: <p>I'm trying to check Windows Event log for the past 12 hours (or 8hrs) by using CheckEventLog command and I'm getting random results with this command. It works in one place and it doesn't in other places. I have NSClient ++ version (0.5.0.62) installed on all my Win servers.</p>
  
  <p>The command I'm using:</p>
  
  <pre><code>$USER1$/check_nrpe -H HOST IP -p 5666 -c CheckEventLog -a file=Application MaxWarn=1 MaxCrit=1 "filter=generated &gt; -12h AND severity = 'error'" unique  descriptions "syntax=%source% - %severity% - Error Details: %message%"
  </code></pre>
  
  <p>I get the result as:</p>
  
  <pre><code>UNKNOWN-CHECK_NRPE: Invalid packet type received from server.
  </code></pre>
  
  <p>If I remove '-' on the right of the 12h it shows OK result, but doesn't report any errors (I know there are errors in the event log as I'm viewing them at the same time). 
  If I add the '-' on the right of the 12h, like this "-12h" it will return Unknown.</p>
  
  <p>What is wrong here? have I missed something?</p>