Can't get plugins to work on vBulletin version 3.5.2

[slackovic]

When I install new plugin and set it's location (hook location) to be, i.e. forumhome_start, nothing is being displayed on the homepage of my forum.

I'm using plugin to display banners. It worked before (on vBulletin version 2.x), but now, after I upgraded vBulletin application to the version 3.5.2, nothing is being displayed on the pages where banners should be. When I delete all the plugins, everything works fine.

Even if I enter echo 'Hello'; nothing is being displayed...

I asked that question on vbulletin.com forum but they told me to try asking it here.

thanx in advance