Perhaps your traffic level was set to 0%? You can set your traffic level at the Options>Settings>ATC.
Remember that everything you recompile the traffic.bgl file, you only load whatever is in your FlightPlans.txt file and not it in addition with the defualt FS2002 AI Traffic!
If you would like to restore your original AI Traffic, look for traffic.bgl in your FS2002 CDs and copy it over to your "C:/Program Files/Microsoft Games/FS2002/SCENEDB/ATC/Scenery" folder, overwriting the file there.
DMK(TG773/772) PEN(SQ772/MH734) PER(QF333) PEK(CA763) HKT(MI320) HKG(SQ744) ICN (OZ333), CJU,TAE(OZ734) TPE(3K320) KUL(T