IAX trunk - ztdummy


i have two asterisk servers connected via IAX trunk.
When reloading settings every time i geting:

[Aug 11 15:03:08] WARNING[10411] chan_iax2.c: Unable to support trunking on user 'asterisk2' without zaptel timing

lsmod shows:Module Size Used by ztdummy 38856 0 zaptel 231496 13 ztdummy

in CLI: zap show status

Description Alarms IRQ bpviol CRC4 ZTDUMMY/1 (source: RTC) 1 UNCONFIGUR 0 0 0

Any idea why trunking do not work?

ztdummy should start before asterisk?

Best regards