echo"<div class='warn'>Apparently something went wrong executing the command or writing the output.</div>";
echo"<br />Is ".$filter." (usually part of GraphViz) and echo installed and able to be executed by the webserver process?";
echo"<br /><br /> Is your webserver restricted from executing command line tools through the <code>system()</code> call (PHP Safe Mode or SELinux)";
echo"<br /><br /> Is ".$config["attachment_store"]." writeable by the webserver process? To change this do the following (POSIX-based systems): chown <apache user> ".$config["attachment_store"];