If you have a hunt group name which matches the VMPRO module name it should ring there if VM is down.
Also, to clarify.
Ringing is to a hunt group?
If so,
Copy, and paste existing hunt group(we will call it AAA here) to create new one, name it BBB
Set up time profile SHORTRING.
Set ICR to Destination hunt group AAA
Set ICR to hunt group BBB for night service destination
Set night service profile to SHORTRING
Record the hunt goup BBB greeting to match HG AAA, or just copy and paste its greeting in on the VMPRO server, if you know how. Then adjust the timers on the second hunt group to change the time before it goes to VM to the time you want. The caller will not know it is a different HG.
IN VMPRO, you can create a LEAVE custom hunt group start point for hunt group BBB, leading to a leave mail action specific tab AAA hunt group mailbox number so they only have one to check.