Code Formatting problem

WordPress 3.5.1
Tested on Chrome and IE9

The plugin works as far as putting the code in to a “code block” and the line numbers work, however, the code syntax isnt coloured.
ie.
<?php echo “blah” ?>

< > dont display green
?php isnt bold

etc…

i have tried with different variations on the setting, but no luck.

https://www.ads-software.com/extend/plugins/devformatter/