Cisco phone extension will not go into voicemail when used as rollover

We have an extension set up in our Cisco Unified CM.  If you dial the extension directly, it will ring, and if not answered, it will go into voicemail.  However, the extension is also set up as a rollover number for another line.  We would like if someone calls the other line and is not answered, it would roll to this line, and if not answered, it would dump into the voicemail.  

However, although it works properly when dialed directly, if someone dials the other number, it will roll over correctly, but then rings five times, and goes to the system recording instead of voicemail.  We are running version 9.1.  

Anyone have any ideas?

Thanks!