Meet me cannot run on Asterisk/1.6.1-rc1

I’m using CentOS 5.2 with Asterisk/1.6.1-rc1 + Dahdi

While I’m joining to the Meetme conference, the console has the following error:

 -- Executing [6301@DLPN_Default_Dial_Plan:1] MeetMe("SIP/6000-0a1a16d8", "6300,MxaA") in new stack
[Feb 17 16:44:29] NOTICE[7951]: rtp.c:1089 process_rfc3389: Comfort noise support incomplete in Asterisk (RFC 3389). Please turn off on client if possible. Client IP:  == Parsing '/etc/asterisk/meetme.conf':   == Found

[Feb 17 16:44:29] WARNING[7951]: app_meetme.c:861 build_conf: Unable to open pseudo device == Spawn extension (DLPN_Default_Dial_Plan, 6301, 1) exited non-zero on 'SIP/6000-0a1a16d8'

I google it for couple of hours, see that some are “Mismatch Character Case”, and others which I found that not the reason causing that problem,
may I know how to solve it?

Thank you very much

Meanwhile, there are many “output” at the console… here are some of them, but it seems does not affecting asterisk, so i simply ignore them…

fd == -1 in astman_append, should not happen

== Spawn extension (asterisk_guitools, executecommand, 2) exited non-zero on ‘Local/executecommand@asterisk_guitools-8805;2’

Thanks all first…

after more google…
found that in dahdi-tools, run “make config”, and need a reboot, finally dadhi detects no hardware telephony and will create dadhi-dummy and the conference function works now, thanks.