Pilot voice not activating

[donair]

I have a problem with just one particular aircraft....the FS2k2 default 747 (Global, Landmark etc..) All of my other aircraft are no problem at all.

I haven't used the default 747 for some time now but on using it today the following fault occurred.

I transmit to ATC and hear no pilot voice.  I know the message has gone because I then hear ATC acknowledge me.  If I tap the 'Q' key very quickly 'off' and 'on' I just about hear the tail end of my transmission.

Can some one please advise me if there is some part of the aircraft.cfg or some other file that needs looking at in order to activate the pilot voice?

Thanks to you all

Don