How to solve this internal error in redmine

When i try to connect database in redmine custom workflow and click on SAVE,I get Redmine Internal Error.Please find the code below

@connection = ActiveRecord::Base.establish_connection(
:adapter => "mysql2",
:host => "localhost",
:database => "bitnami_redmine",
:username => "bitnami",
:password => "xxxx"
)

Please help me to solve this :-(