Sound Blaster PCI 512: sound through the speakers, none to the applications

Other people have reported this behavior on this and the German
multimedia list, but I haven't seen anyone post an answer that works.

I've got SuSE 8.1 with a Creative Labs Soundblaster PCI 512.  I checked by modules.conf
file, and all the lines that the ALSA documentation say should be
there were put there by YAST.

I'm trying to record (using record or audacity or broadcast2000) from
a cassette deck hooked to the the line-in input on my soundcard.
Although I can *hear* the sound from my tapedeck fine through the
speakers, no app seems to be able to get the sound. Nothing shows up
on the meters, and if I save the files and play them, no sound is
there. 

I am using alsamixergui, and have the line-in set as the recording
input (with the little red "light" icons).

Any suggestions?