asterisk users - Mar 2005 - 3 Party Conference & ZapHFC

Hi *s,

I'm  using  the  zaphfc driver to use HFC based isdn card for a
self-made  ISDN  S0 bus. An ISDN Phone is connected to this bus
and  works perfectly. I can make outgoing calls to PSTN and SIP
users.

My question is related to ISDN features:
* switching multiple calls is no problem
* connecting two calls I've made works well
* music on hold works well

But when I try to activate a 3-party conference, I see an entry:
"Facility name requested on channel 0/2 not in use on span 1"

So my question is: Can I do anything to make this feature work?

Thanks for your help,

Dominik