bbPress.org

That last plugin hasn’t been updated since January and is only compatible up to wordpress 2.7. It only adds a default role to bbpress, but if you’ve matched your wordpress and bbpress roles, this isn’t necessary, if it ever was.

A plugin should not be necessary in order for someone to register on a wordpress blog or on bbpress. Under the Settings/General you have a place to set the default role for new members; Subscriber, Administrator, Editor, Author, or Contributor for wordpress and those roles can be matched up to bbpress roles under Settings/WordPress Integration.

aMember.com mentions wordpress integration but not bbpress on their site, so I think that might be the issue.