Vienna

Hello I just purchased the A340 and installed it. So far (except a few loading problems now and then) the add on works......but....i fly mostly online on VATSIM and therfore I have to use the ivap plug-in for radio communications. And this is a problem with my A340-300 installation. Normally I start the flight and then connect to the Vatsim network.....which I can do successfully with the A340 add-on. But then, when I try to communicate with ATC (headphone) I push the push-to-talk button, which is my Button 1 on my flightstick, nothing happens. I simply cant transmit any voice message. There is no green light on ivap plug-in indicate the transmission. With any other aircraft loaded, it works fine.....just the A340 wont let me transmit with ivap plug in. What i find out was, I couldnt even hear transmissions from ATC also, but I found out that a Button on the COMM Panel has to be pushed (light on) then I was able to hear ATC transmissions.....but.... still cant transmit my own messages via voice. Any other suggestions for me? Thx for help.