737 Next Gen and 737 800/900 install problem

I install the first one and it chooses just the C: directory, it installs fine. I then install the 737 800/900 file and it installs fine too. When I am in FS9, I have no option to choose any of the 800/900 aircraft. I uninstalled both PMDG packages, reinstalled the first one...navigating to my FS9 directory, installed fine. Went to install the 800/900 pack, and it keeps saying that I need to install the first one. I also tried manually placing the files in the proper locations, but FS9 didn't like that, so I had to reinstall FS9. I have it fresh right now and am looking for assistance to get these in the air and working properly. Would greatly appreciate any help. Thanks.