Why is it that mods work 50% of the time?

[SkootchNasty]

Sometimes when i start a game up, all of my mods will be up and running (i always check to make sure none of them are conflicting with each other) and the other half of the time they just dont run at all, even on a mod map. This makes no sense to me as i am doing nothing different, nor am i downloading new mods. can anyone give any advice? Am i doing something wrong?

[LucK_]

Mods often don't work on official servers.

[Ascerta]

I don't know what kind of mods you are using, but mines always work. When you start your game (L4D2.exe), make sure all addons are loaded before joining any games.

[Stark Raven]

Quite probably it's because you're connecting to pure servers. Any server with the variable "sv_pure" set to 1 (active) will enforce vanilla gameplay no matter what. You can tell which servers are pure by using custom loading items such as the spinner, loading bar or posters, or you can use the developer console. The sv_pure readout will be right below the IP and game info when you connect.

[SkootchNasty]

Okay i will start doing that, thank you! Usually what i try to do is start a game by myself and leave it open to the public, usually that lets me but i just could not get them to work at all today until like 6 games later