Our plugin uses XSLT for rendering HTML, so you need to turn on your XSLT Processor.
For Unix users:
1) From terminal run the command sudo apt-get install php5-xsl.
2) Install it and then restart your server.
For Windows users:
1) You can find the line extension=
2) Then restart your server.
If you cannot find your php.ini file, you can contact your hosting provider and ask for XSLT Processor to be enabled.