Problem:
User has a Zoo 6 SR0 with Rhino V5 and V6 keys in it.
Rhino V5 will get a license but Rhino V6 will not.
Fix:
The Zoo 6 SR0 on their system has a 2015 build date. They need to download and install the newest Zoo 6 SR0 from 1/9/2018,
-and-
Then they need to remove and add the V6 license keys from the updated Zoo.
Then V6 will successfully get licensed from the LAN Zoo and run.