Wait a minute. Maybe I'm missing something, or misunderstanding your description. You wrote "
THen when I install the 15. Uboat missions it will install without issues. I again don't get prompted for registration key to input. After I install the patch I try to run the game and receive "Sh4.exe."
SHIV (U-Boat missions) is the latest version and doesn't (to the best of my knowledge) require a patch. Are you saying that you're trying to install a patch after installing version 1.5?