microphone doesn't react on 10.1

Hi,
in order to use Skype on my laptop, I am trying to figure out how to
get a microphone to work; I am running the machine under 10.1. The
soundcard is identified as an ICH7 one, and a couple of other
sound-related apps (realplayer, fluidsynth, rosegarden, ...) work
correctly and well. The only thing that doesn't seem to react is the
mic, regardless whether I try to use the built-in or plug in an
external one.
In YaST, the soundcard settings are PCM 87, headphone 100, Micro 100,
Front (whatever that is) 68. I have fired up KMix and made sure that in
"Output" the mic is active, that in "Input" Capture is set to the
highest value on all 3 slides, and that in "Switches" Mic is set as
input source. I then tried to record some noises with KRecord, but
nothing is recorded and indeed the Input level meter doesn't react
either, indicating that the mic is inactive. However, when I unplug the
external mic, the speakers make a noise; furthermore, there is a small
change in theKRecord input level meter if I switch off the leftmost
input channel in KMix's Input panel.
So - what might be the problem, and what else could I try?
Tom

.