help :/

[Muse]

ok i need help, i have a game on my comp (full version) and i also have the expansion (but not on my comp), when i try to install the expansion (the instalation process is exactly like d2 but different games) it says i need the full version of the original game (im guessing the game isnt counted as a program becuase its not in my add/remove program directory, i just copied and pasted the already installed game from disk to my hard drive). so i need to know how i can get the expansion to notice the original version or i just need the files from the installation from cd onto my comp, help is greatly apreciated .