[Operators] fallback, gmail and s2s

[sergio]

Hello.

I've already tried to solve this problem in ejabberd maillist, ejabberd 
forum,
and ejabberd jabber room, but without success. May be here somebody can help
me.

I have jabber server which works fine even with gmail. And I want to add
fallback sever.

DNS looks so:
_xmpp-client._tcp.my-jabber.tld. SRV 10 0 5222 master.tld.
_xmpp-server._tcp.my-jabber.tld. SRV 10 0 5269 master.tld.
_jabber._tcp.my-jabber.tld.      SRV 10 0 5269 master.tld.

_xmpp-client._tcp.my-jabber.tld. SRV 20 0 5222 slave.tld.
_xmpp-server._tcp.my-jabber.tld. SRV 20 0 5269 slave.tld.
_jabber._tcp.my-jabber.tld.      SRV 20 0 5269 slave.tld.

When I turn off master all works fine except gmail.com.  From the start
ejabberd on fallback server I see three "wait for validation" errors:
Trying to open s2s connection: jabber.ru.net -> gmail.com with TLS=false
wait for validation: jabber.ru.net -> gmail.com (closed)

And one "invalid dialback" error:
Trying to open s2s connection: jabber.ru.net -> gmail.com with TLS=false
Closing s2s connection: jabber.ru.net -> gmail.com (invalid dialback key)

And many "wait for validation" errors after that.

Does anybody have fallback jabber sever which works with gmail?
Does anybody have any experience in fallbacking jabber?

--
sergio.