Filewatcher returning error. No overload matches delegate
<p>I've written this method which should check for file changes.</p>

<pre><code>public static void watch()    
   {    
        FileSystemWatcher watcher = new FileSystemWatcher();    
        watcher.Path = ConfigurationManager.AppSettings["OpticusFileLoc"];    
        watcher.Filter = "sigtrades.xml";    
        watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
       | NotifyFilters.FileName | NotifyFilters.DirectoryName;    


       // watcher.Created += new FileSystemEventHandler(OnChanged);
        watcher.Changed += new FileSystemEventHandler(OnChanged);

        watcher.EnableRaisingEvents = true;

    }
</code></pre>

<p>However, I get this error:
"No overload for 'OnChanged' matches delegate 'System.IO.SystemEventHandler'</p>

<p>Where am I going wrong?</p>
