One further thing you might want to try is installing AIBridge (v2.4 if you run FS2002, v3 if you run FS2004) It injects online traffic back into the FS AI tables using facilities in FSUIPC. SB doesn't always do this so well (authors' words, not mine), but since we started using IVAP on IVAO I've not needed to use AIBridge at all.
Unfortunately, the website of the gentleman that writes this excellent piece of software has been suspended. [strike]I'm going to trawl my harddrives to see if I have a copy of v3, but please don't hold out for me finding it...[/strike]
EDIT: Well blow me, found a copy of the zip for the most recent V3. [
Link to download ]