So, when Ioaded the game on March 30th of this year, I couldn't get into a versus match. So, I tried Scavange. I also couldn't join a single match. Then, I tried Realism Versus. What do you think happened? I STILL COULDN'T JOIN! Everytime I try to join a commpetetive gamemode, E.I. Versus, Follow the Litter, TAAANK!, Scavange, it tells me to download an addon by Valve. When I go to the page, it is L4D2's store page.
Before anybody tells me reinstall, I would like to inform you that I did reinstall; five times with no resault. Tried removing all the mods, I couldn't do anything. I really want to play versus again, and if this countinues I won't play L4D2 anymore. I saw somebody with a similar problem, so is L4D2's servers just bad this month? Or is this a real, big, glitch?
Please let me know how to fix it.

~Myself