asterisk users - Feb 2005 - Context fails so falling back to extension "s" ?

I realize it's bad form, but I'd really appreciate some hand holding
here. AMP is making me pull my hair out and the mountain of
configuration data in extensions.conf is starting to get to me...

I have the first channel configured in zapata.conf to "take" incoming
contexts to "from-pstn". I'm using AMP neat "Incoming
Calls"
configuration page and extensions-additional.conf's include statement
is uncommented. The damn thing still doesn't work...

I get this error when calling in:

Feb 10 15:55:17 VERBOSE[3477]:     -- Starting simple switch on
'Zap/2-1'
Feb 10 15:55:22 ERROR[3477]: fsk_serie made mylen < 0 (-46)
Feb 10 15:55:22 WARNING[3477]: CallerID feed failed: Success
Feb 10 15:55:22 WARNING[3477]: CallerID returned with error on channel
'Zap/2-1'
Feb 10 15:55:22 VERBOSE[3477]:   == Starting Zap/2-1 at from-pstn,s,1
failed so falling back to exten 's'
Feb 10 15:55:22 VERBOSE[3477]:   == Starting Zap/2-1 at from-pstn,s,1
still failed so falling back to context 'default'
Feb 10 15:55:22 WARNING[3477]: Channel 'Zap/2-1' sent into invalid
extension 's' in context 'default', but no invalid handler


Extension 's'? I thought 's' meant Start, not an actual
extension. If
there's something I'm not reading or need to read again, don't
hesitate to hit me with a clue stick.

Regards,
aaron.glenn