Hello.
I wanted to jump in here and say that this same issue is happening with my father's new Jetline system he just got. When FsRaas is running it shows connected. When taxiing to a runway FsRaas says "Approaching" and that's all. Different airports, different runways, different aircraft... that's all that happens. No other sound is heard the entire time. If everything is quit and started again, the exact same thing happens. Only the very first word FsRaas is trying to play is heard and nothing more.
FSUIPC 4.937 with FSX.
Using FSUIPC 6.995 with FS9 and it works fine there.
I too am searching for an answer to this but so far have come up empty.