Signalling requested on channel 4 is Unknown signalling -1 b

Hi,
There is an error when running ‘zap restart’ in asterisk console:

[color=blue]CLI>zap restart
Destroying channels and reloading DAHDI configuration.
[Apr 21 09:32:54] ERROR[11540]: chan_dahdi.c:7674 mkintf: Signalling requested on channel 4 is Unknown signalling -1 but line is in FXS Kewlstart signalling
[Apr 21 09:32:54] ERROR[11540]: chan_dahdi.c:11270 build_channels: Unable to register channel ‘4’
[Apr 21 09:32:54] WARNING[11540]: chan_dahdi.c:10482 dahdi_restart: Reload channels from dahdi config failed![/color]

zapata.conf is defined in mysql using static realtime.

Any idea?!