asterisk users - Oct 2006 - question about asterisk txFAX

I have installed the libtiff(3.5.7),spandsp-0.0.2pre24,app_txfax and
app_rxfax,asterisk-1.2.12.1 on the CentOS 4.2.
	
	I set sip.conf like this:
	[sip_local]
	host=192.168.2.111
	type=friend
	dtmfmode=rfc2833
	canreinvite=no
	insecure=very

	I set extensions.conf like this:
	[test]
	exten=>_9001XXXX,1,Set(CALLERID=${EXTEN})
	exten=>_9001XXXX,n,dial(SIP/${EXTEN}@sip_local)
	exten=>_9001XXXX,n,hangup

	[fax]
	exten=>_9002XXXX,n,SetVar(FAXFILE=/var/spool/asterisk/fax/test.tif)
	exten=>_9002XXXX,n,SetVar(FAXFILENOEXT=/var/spool/asterisk/fax/${CALLEEID})
	exten=>_9002XXXX,n,txfax(${FAXFILE})

hen I dial 9001XXXX,it's OK,but when I dial 9002XXXX,it faild fax,I
thought that maybe I had not set the sip_local in the [fax] config
session,but how can I set that?

I search on the google net, but have no idears about this,how can I
send the fax out?

	Thanks for any hints!
	fangh.