[linux-audio-user] rec creates empty files, play plays nothing

[millward]

I've tried this for Red Hat 7.3, Slackware 9 and 
Slackware 10, but so far, no luck.
I'm trying to create a WAV file with my guitar.
First, I set the software mixer for line-in and line-in gain,
and for PCM and master volume for playback and
active everything on the mixer I can, just out of desperation.
I then use the command line in a terminal window:
 rec -V -r44100 -c2 -s -w  new_file.wav
  Is this command OK or did I goof?
My sound card is a Creative Sound Blaster Live 5.1.
I'm using line-in which is a blue plug on the sound card.
I've tried various methods to input sound, such as:
 guitar->adapter plug->sound card line-in
 guitar->Eurorack UB802 mixer->adapter plug->sound card line-in
 guitar->Eurorack UB802 mixer->amplifier->adapter plug->sound card line-in
 guitar->amplifier->adapter plug->sound card line-in
  I can hear my guitar input through my computer speakers so I know
the signal is going into the card and coming out of it.
    In all cases the WAV file is created with no error messages.
I then try to play it back using:
   play -V new_file.wav
In all cases, there is silence. Nothing at all and no error messages.
I've tried all kinds of variations on the rec command and have
set the volume higher, lower, whatever.  So far, nothing.
I must be doing something really dumb, but I don't know what.
Can anyone tell me how to create a WAV file using rec and get
it to play?  A couple years ago I did get good results using rec and
play, but I've lost the notes I made and can't remember how.
I'm not happy with myself for that.
 Any information would be very welcome!