OK, two possibilities then, since your code worked before and doesn't now.
First, did you change phones between the time that your code worked and now where the code doesn't work? BerryBuzz keys are tied to your phone's PIN, which is unique to each Blackberry. Tying registration keys to PIN's is a standard practice for for registration keys.
Second, assuming that you did not change phones, is it possible that the first time around, you used BerryBuzz version 1.x and now you are trying to use the v1.x key with version 2.x? Because v2.x is considered a major upgrade over v1.x, Bellshare changed the registration key system. That is, even if you are using the same phone (and therefore same PIN number), the key is different. There is an upgrade fee (less cost than buying v2.x as a first time registrant) to upgrade from v1.x to v2.x.
If this applies to you, and you decide you don't want to pay the upgrade fee nor do you wish to purchase the new version, you may want to look around and see if you can still find version 1.x somewhere and use your key with that.
I saved you some time and searched for you. You can download version 1 via OTA link: http://m.bellshare.com/downloads/ber.../berrybuzz.jad