Redmine

Hello. I've tried following http://www.redmine.org/projects/redmine/wiki/RedmineInstall to install redmine from scratch and do mysql dump / mysql restore, but I failed. After that, I've tried http://www.redmine.org/projects/redmine/wiki/RedmineUpgrade and I failed again. Can you tell me what's the recommended way to upgrade debian/redmine from 5/1.0.1 to 6/1.2.1? I didn't want to post any error message as there's a mess among them because I've experimented with ... I can't even remember what not. Once I figure out what's the best way to upgrade / install + migrade DB, I'll post meaningful error message. Thanx in advance!