NMM not working with fallout 3

[DeadlyDoughnuts]

I recently bought Fallout 3, however whenever i try to install a mod through NMM i get an error saying "Nexus Mod Manager is not set up to work with Fallout 3, if Fallout 3 is installed rescan for installed games." Despite being set to the right directory (C:\Program Files (x86)\Steam\steamapps\common\Fallout 3 goty) it still won't reconize Fallout 3 and no matter how many times i rescan it dosent work. Is there something im missing because im not sure why this would not work. Any help would be appreciated, thanks.