No, that's entirely different.

If it works in HLMV then the export was correct. Perhaps the game simply doesn't support this feature.

A corrective shape keys is one with a name consisting of the names of two ore more OTHER shape keys, separated by underscores.

Smile
Frown
Smile_Frown <- this is a corrective shape key

This will be fixed in the next release. For now, you can work around the issue by increasing the DMX binary version to at least 4.

I've found the problem now. This only affects very old versions of DMX binary encoding.

I'll release an update soon. In the meantime, please try exporting your files with DMX binary 4 or later. You can have this configured automatically by selecting the appropriate engine path.

Please upload a DMX file which demonstrates this problem.

It's very difficult. You'll have to look this up online as it's a general modelling task and not related to the Blender Source Tools.

The skeleton of the mesh must be identical to the skeleton which the animation targets. You will need to change either the model or the animations to make this happen.

Please upload one of the affected DMX files.

Please upload your Blend file.