ATC problems on ground

For some months now I've been getting (intermittent) problems with ATC (on the ground) directing me to a gate or parking after landing, only for me to find another aircraft there when I arrive (not a static a/c). Or, as just happened, an a/c landing just behind me is directed by ATC to the same gate they have just told me to taxi to.This can happen at any airport as far as I can see. I've checked for multiple AFCADs or for errors in the AFCAD file(using AFCAD2). I have Ultimate Traffic, and have recompiled the traffic.bgl file more than once, but it wouldn't be the fault of UT that ATC is directing more than one aircraft to park at the same gate. Seems to me to be an FS9 issue.Anyone any ideas on this? I've turned my traffic down a few %, not sure yet if this will help - it's a long process troubleshooting this of course - but this shouldn't really be happening, whatever the settings, should it? What files other than traffic.bgl might be at fault here (I could perhaps replace them)?Thanks,Martin