我正严格按照本指南进行操作：在Redmine服务器上安装积压模块：https://backlogs.github.io/www/en/installation.html
尽管如此，这会发生：
root@tannenfels:/var/www/redmine# bundle exec rake redmine:backlogs:install --trace
rake aborted!
Don't know how to build task 'redmine:backlogs:install' (see --tasks)
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/lib/rake/task_manager.rb:59:in `[]'
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/lib/rake/application.rb:159:in `invoke_task '
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/lib/rake/application.rb:116:in `block (2 le vels) in top_level'
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/lib/rake/application.rb:116:in `each'
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/lib/rake/application.rb:116:in `block in to p_level'
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/lib/rake/application.rb:125:in `run_with_th reads'
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/lib/rake/application.rb:110:in `top_level'
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/lib/rake/application.rb:83:in `block in run '
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/lib/rake/application.rb:186:in `standard_ex ception_handling'
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/lib/rake/application.rb:80:in `run'
/var/www/redmine/.gem/ruby/2.3.0/gems/rake-12.3.1/exe/rake:27:in `<top (required)>'
/var/www/redmine/.gem/ruby/2.3.0/bin/rake:23:in `load'
/var/www/redmine/.gem/ruby/2.3.0/bin/rake:23:in `<main>'
似乎所有的依赖项都已解决，并且tar.gz模块存档位于正确的位置。我在做什么错了？