Ring group firstavailable strategy not ringing the next available

Configuring a Ring Group with firstavailable strategy doesn´t ring the next extension if the last is UNAVAILABLE (Not registered)

I have 7 extensions in the Extension List (all of them are SIP Channels), the first extension is Unavailable (not registered), so when the call flows to ring group, it try to ring this extension and then "Subscriber absent")

I attached log of the call... Note the extensions 1700 before the call, its absent, so it´s no the "first available" on the extension list.

"sorry for my english"