I purchased Tower 3D Pro, Real Traffic, KATL Real Color, and KATL Tower3D Pro today. KATL wasn't showing up but all the other packs seemed to work. All I did was re-run the install file. Look at the destination directory. It wants to go to ../Tower3D when Tower3D Pro is installed. Just change the destination folder to your Tower3DPro folder (do not drill down into the Extension folder). Example: C:\ProgramFIles (x86)\Tower!3D Pro\ If you tried to install the expansion airport before, you will see the Tower 3D folder... DO NOT USE THAT FOLDER. Use the Tower!3D Pro folder; i.e. C:\ProgramFIles (x86)\Tower!3D Pro\ My KATL airport is now white in the menu..showing active. Hope that helps someone.