[Plugin: Mark Unread Comments] Does not add the class. Anyone could fix this?

Hello folks.

This plugin is what I was looking for (and no other plugin does it as simply as this one). However, it has several problems :

Serialize/Unserialize problem, which I managed to fix by replacing unserialize and serialize by maybe_unserialize and maybe_serialize respectively.

However, even with this fix, the class “unread” is still not added.

Any help would be greatly appreciated ??

Thanks.