Redmine-update 0.8 to 2.1.4 for db

Hi everybody,
Today and yesterday ><, i try to install my old db on redmine 0.8 for the last version version 2.1.4, each time when i try the helper , my version dont work, for now im in 2.1.4 but without DB, the question is..

How i can do when i would like install my old DB with my new version :)

( sorry for the bad english, i work on too ;) )