FS9 don't like me using traffic :(

Hi all,
Can anyone tell me why everytime i load fs, it resets my traffic density to zero? It ALWAYS does it when i install some new scenery, and usually does it when i restart the game. Its no big hassle resetting the traffic, its just annoying because sometimes i forget.
Any ideas anyone? BTW. I am using Project AI. If this is relevant.
Thanx.
Stephen.
Can anyone tell me why everytime i load fs, it resets my traffic density to zero? It ALWAYS does it when i install some new scenery, and usually does it when i restart the game. Its no big hassle resetting the traffic, its just annoying because sometimes i forget.
Any ideas anyone? BTW. I am using Project AI. If this is relevant.
Thanx.
Stephen.