Nothing is broken and all voice lines work, but some of them simply can't work specifically in Survival and Scavenge game modes. This is defined in the game's response system (talker).

Furthermore, you might played on server(s) with modified talker add-on installed. In that case some lines might not work or can give you different responses. Some server admins even install Vocalizer Fatigue plugin which can severely limit how much people can use vocalizers.

I'll also mention that when playing Versus or other competitive game modes all add-ons are disabled by default, so vocalizer won't work either (there are guides on how to change this if you're interested).

Most important things to know on how to use vocalizer are already explained on the vocalizer's Workshop page description, so I always recommend read it very carefully, especially HOW TO USE and IMPORTANT TO KNOW parts.