Please be specific. What steps are you performing, and what is happening when you perform them?

I import a .SMD sequence, specifically c4m1_intro_gambler.smd found in anim_gambler.mdl in L4D2, the skeleton of the survivor appears, but when I look at the frames in the Blender timeline, all frames are the same, there is no movement.

Nothing happens in that animation until frame 80. Try skipping there.

I just don't know what I'm doing wrong, I click on the lines the timeline has but they are all the same, is there something else I'm supose to know? Which object to click? Some other process it needs?

As long as you're not in edit mode, that should be it.

Are you trying to import a decompiled animation or the file provided in the L4D2 authoring tools?

A decompiled animation file, but yeah I can't get it to work.

It's possible that the decompiled file is bad. Try Valve's version: Left 4 Dead 2\sdk_content\Starter_Kits\Survivors\L4D2\Nick\models\survivors\Compiling Files\dmx\animation\c4m1_intro_gambler.dmx

How did you get a sdk_content folder?

Install the Left 4 Dead 2 Authoring Tools from the Tools section of your library.

Mine doesn't do that, a folder like that doesn't appear, I have Authoring Tools [Beta] (Not the Left 4 Dead 2 Beta)

Nvm, I verified cache and it appeared. Thanks.