asterisk users - Aug 2005 - ChanIsAvail for IAX not working again/still? AKA Redundant IAX connections not working

Hi -

I'm running CVS-HEAD from 2005-08-11 20:17:17 UTC, and I'm trying to  
set up some redundancy on IAX connections between locations.  I have  
two IAX peers set up that work correctly by themselves: "ast551-out"  
and "ast551-out-backup":

[ast551-out]
type=peer
secret=secret
username=ast551
host=X.X.X.X
qualify=1000
disallow=all
allow=gsm
allow=ulaw
trunk=no
tos=0x04

[ast551-out-backup]
type=peer
secret=secret
username=ast551-backup
host=Y.Y.Y.Y
qualify=1000
disallow=all
allow=gsm
allow=ulaw
trunk=no
tos=0x04

If one does become unavailable, I'd like the other to be used.  I  
tried to set that up like this:

exten => 145,1,ChanIsAvail(${IAX2/iax-in:secret@ast551-out-backup}/$ 
{EXTEN})
exten => 145,2,Dial(${IAX2/iax-in:secret@ast551-out-backup}/${EXTEN}, 
20,t)
exten => 145,102,Dial(${IAX2/iax-in:secret@ast551-out}/${EXTEN},20,t)

What is happening is that all calls are going out through "ast551-out- 
backup", even when I physically disable the connection.  The console  
shows this:

     -- Hungup 'IAX2/ast551-out-backup-2'
     -- Executing Dial("SIP/68-1c7a",
"IAX2/iax-in:7436@ast551-out-
backup/145|20|t") in new stack
     -- Called iax-in:7436@ast551-out-backup/145
     -- IAX2/ast551-out-backup-7 is circuit-busy
Aug 26 12:11:56 NOTICE[14283]: chan_iax2.c:2736 auto_congest: Auto- 
congesting call due to slow response
     -- Hungup 'IAX2/ast551-out-backup-7'
   == Everyone is busy/congested at this time (1:0/1/0)

Doing an "iax2 show peers" shows ast551-out-backup to be offline:

ast33*CLI> iax2 show peers
Name/Username    Host                 Mask             Port           
Status
astnh-out/ast55  Z.Z.Z.Z   (S)  255.255.255.255  4569           
Unmonitored
ast551-out-back  Y.Y.Y.Y   (S)  255.255.255.255  4569           
UNREACHABLE
ast551-out/ast5  X.X.X.X   (S)  255.255.255.255  4569          OK (25  
ms)
3 iax2 peers [1 online, 1 offline, 1 unmonitored]


Have I bumbled a configuration, or is my method incorrect? Or is  
there a bug?  Should ChanIsAvail report that ast551-out-backup is  
unavailable if it fails to qualify?

Thanks,
Noah