Hello,
Just had the answer from the mailing list (thanks Luke), it also needs this to be added :
jimport( 'joomla.html.parameter' );
added just afterjimport('joomla.plugin.plugin');
into :
plugins/system/gantry/gantry.php
Original problem here :
www.kunena.org/forum/167-k-16-test-repor...jparameter-not-found
Might be concerning a lot of plugins !