HELP! No Precached Model?

[Anthem]

Well I tried to start a Single Player The Passing game. When it had loaded the game crashed and this appeared. 5/ - survivor_bot: UTIL_SetModel: not precached:
Models/survivors/survivor_biker.mdl.
When i tried again it said the same thing but had teen_angst.mdl .
Any help will be appeicated :D

[Chaos Mana]

Try vertifying your game Cache in the Properties setting, that usually fixes missing items

[Rayman1103]

Yes, try verifying your game cache. If that doesn't work, it's probably an addon causing the problem. I know an old population.txt file would cause this issue, as it doesn't contain the data to precache the L4D1 survivors in The Passing.

[Anthem]

THX IT WORKED! (Rayman1103, u have an awesome custom mutation add on)