Debian installation with a hardware synth for speakup

[Pawel Loba]

Hi,
By specifying speakup.synth=dtlk at Debian Squeeze installation line I got
my system talking via my external DoubleTalk synthesizer at the first run
after the installation process.
I tried to do the same on my friend's system who is using Apollo synthesizer
by putting speakup.synth=Apollo at the installation line but with no luck
this time.
This is probably very trivial question for all of you gurus out there but
perhaps someone would give me some suggestion how I can fix this and make
speakup talking via Apollo synth, please.
Thanks a lot.
Pawel.