If you go to addons, are their names both white or red?
In my latest L4D2 screenshot you should be able to access a list of most of the add-ons I had active at that time. It's a bit too much to type all of them here.

One of the maps on which it certainly works for me is No Mercy, at the start when you enter the apartments there are some paintings immediately.

which other addons do you have installed?

i tried it about 2 months.

Have you tried on different maps? There are some maps that use different paintings so it doesn't work there. I've just tried on two different campaigns with paintings and the mod works there.

Yes, i have.

@KampfkrûmelLP
Did you get both the Landscape and Portrait format mods (if it didn't automatically subscribe to both) ? Since it requires both of them in order to work. If you did and it still doesn't work then I'll have to check what could be wrong, as last time they did work for me.

doesnt work.