Redmine

My first error was on another TABLE. I found that I should specify the DB schema name in database.yml because mine wasn't "public". Now I have this error :

CreateUserPreferences: migrating ========================================
-- create_table(:user_preferences)
NOTICE: CREATE TABLE will create implicit sequence "user_preferences_id_seq1" for serial column "user_preferences.id"
rake aborted!
An error has occurred, this and all later migrations canceled:

PGError: ERROR: relation "user_preferences" already exists

Thanks for your help.