Garrys Mod Downloaded Maps

I have been trying to download new maps and objects for garrys mod and despite the fact that i have portal, team fortress, and L4D, i still cant get some downloads to work

the portal gun was one that i would expect to work but i just get a list of errors on the right of the screen. when it comes to maps i get a pink and black background on everything or errors floating around

do i need to download something else still? i have a brand new alienware laptop so i dont think its a hardware problem

any ideas? everyone else just sounds like they download stuff and it works instantly every time :-\

[editline]10:54PM[/editline]

this is in the wrong area isnt it? shoot how do i delete it?

Don’t worry, this section is suitable for this question.

Left 4 Dead is an engine ahead of Garrysmod, so it can’t load in models/textures. What maps are you having troubles with? Maps that may use a lot of foliage (rp_evocity) would probably use Episode 2 content. While most other maps would end up using Counter Strike Source content.

Also, please notice that Garrysmod won’t switch to the L4D engine because the L4D engine supports a max of 8 players, which won’t be very fun.