Volume control

Greetings
I have Windows Vista 32-bit.
I also have a TV tuner Leadtek TV2000 XP, a keyboard A4tech KB(S)-8 and a
sound card Creative Audigy SE.
I have installed the latest drivers for all of these components.
The problem I have is that the volume buttons on the Leadtek PVR program and
the volume buttons on the keyboard do not work. That is, they have no effect.
The sound card works fine in my opinion, I hear what I'm supposed to hear,
but the only sound volume control I can use (the only one that works) is the
one from Windos Mixer. Sound control on all of the other applications which
have sound control does not work.
If anybody has encountered this problem, please tell me what to do.
Thank you
Kali