Damn that sucks

I'm trying to import hl2 citizen models to Blender, and the VTA vertices don't link to the mesh (screenshot to show: https://www.flickr.com/photos/197882084@N05/52751327044/

There are no error messages, animations work fine with bones it's just the VTA doesn't link. The vertex group for this is separate from the main mesh, which seems weird, and they are just called "Unmatched VTA". I don't know where the issue with this is and how to fix it, if anyone has any ideas that'd be great, thanks.