Hello, thanks for advising, I tried your advise concerning the soundcard, but it plays any music during running FSX, so it seems this part is correct.
Indeed I have lots of addon scenery and actually used runway maker, which created a new r4.cvs file which I placed in the FsRaas map,overwriting the standard one.
I am afraid that this also did not work !
So if anybody else has another kind of solution.
I already did send an email to the developer,but untill now I did not get an answer.
Hans.