I just downloaded and tested both versions with a clean, unmodded game and they worked in high and low graphics so it doesn't look like an issue on this end. A couple possible reasons off the top of my head are:
1. The mod manager is giving you an issue. 2. Another mod is overriding this. 3. You might be trying to install this manually. 4. You might still have an empty .pak file from other manual installations in your game folder.