Asterisk Manager: Originate failed

Hi!

I am using:
[ul]AstManProxy 1.22
Asteriks 1.8.24.0[/ul]

Request:

Action: Originate; Channel: SIP/111; Context: outgoing; Exten: 79269161118; Priority: 1; Callerid: 73 ekutyina <111>; Timeout: 60000; Variable: RequestId=87664

Response:

Asterisk Call Manager Proxy/1.22pre081119; Response: Error; Message: Originate failed; Server: localhost

Fails in 3% of cases.
Repeated request in a few minutes goes well.
What could it be?

Thanx