Trying to figure out Ring Groups

I thought I knew how to get this to work but apparently not.

I have a ring group that contains one extension, group is set to Ring ALL. The destination if no answer is set to another ring group. The second ring group has several phones, also set to ring all. The destination if no answer is set to a voice mail box.

When calls come into the first group the phone works fine. If the call isn’t answered it goes direcly to the destination if no answer of the “second” ring group. The system is 2.10 on Freepbx. I have tried this on two different systems and the results are the same. I also tried to set the extension list in the first group to “extension 100”, Second ring group. And the dest. if no answer to the voicemail. The call still goes to the voicemail without sending the caller to the second group. Have I missed something?