Please help!! Can't record from soundcard

Hi all,

When I play a MIDI file, I route the data via the game port of my
Soundblaster 128 to an external synthesizer (Roland JV1010). No problem
here.
The headphone output of the Roland is connected to the line input of the
Soundblaster. I can hear the music playing through the speakers, connected
to the output of the Soundblaster. Still no problem here.
Now I like to record the sound to the HD. In the application I choose as the
"record device" the Soundblaster. Funny enough I can not record the audio
signal, even though I hear it playing through the speakers. Only if I choose
the wave mapper as "record device", I can record a very faint signal in the
background. This is useless.
What is going wrong? Or is this a limitation of PC architecture? BTW, using
Win2k prof.

Thanks in advance.

With best regards,

Fokke Nauta