I've set up an Installer with different sub-packages and whenever I select one of these sub-packages to install it, the box is checked but no files are moved. All files are flagged as missing, and nothing changes in my Data Files directory.

Am I doing something wrong?

Where is your Morrowind installed?

You'll want to move it out of Program Files. Most people just put in C: Games or straight to C:

It's installed in C:\Games\Bethesda Softworks\Morrowind. My Installers directory is C:\Games\Bethesda Softworks\Morrowind\Installers.