Target must be the same or higher major release... you can mirror 8.2.2 to 8.3 though, just not the other way. Starting with 8.3 though (doesn't help here, but will in the future) there is version flexible replication which is logical replication...so when you go to 8.4, you could mirror 8.4 back to 8.3 with that enabled. Read the best practices before converting though since you can one-wy convert to version flexible, but not back the other way without a rebaseline...