Unless you are running Progress version 8 or TTY mode, you will need to extract adecomm.pl.
This is because the codepreview window contains an editor, which uses the same syntax-coloring editor as the Progress Appbuilder, and adecomm.pl contains the includefiles that makes this possible.
Open a command shell and change directory to your DLC directory. In the following example I will assume this is directory "c:\Program Files\Progress" :
cd \progra~1\progress\gui |