ruby-on-rails – 无法激活mysql2(?> 0.3.10),已经激活了mysq

DEPRECATION WARNING: Support for Rails < 4.1.0 will be dropped. (called from warn at /home/user/.rvm/rubies/ruby-2.1.6/lib/ruby/2.1.0/forwardable.rb:183)
/home/user/.rvm/gems/ruby-2.1.6/gems/signalfx-0.1.0/lib/signalfx/conf.rb:3:in `<top (required)>': Use RbConfig instead of obsolete and deprecated Config.
/home/user/.rvm/gems/ruby-2.1.6/gems/bundler-1.11.2/lib/bundler/rubygems_integration.rb:314:in `block in replace_gem': Please install the mysql2 adapter: `gem install activerecord-mysql2-adapter` (can't activate mysql2 (~> 0.3.10),already activated mysql2-0.4.3. Make sure all dependencies are added to Gemfile.) (LoadError)
    from /home/user/.rvm/gems/ruby-2.1.6/gems/activerecord-3.2.17/lib/active_record/connection_adapters/mysql2_adapter.rb:3:in `<top (required)>'
    from /home/user/.rvm/gems/ruby-2.1.6/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
    from /home/user/.rvm/gems/ruby-2.1.6/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `block in require'
    from /home/user/.rvm/gems/ruby-2.1.6/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:236:in `load_dependency'
    from /home/user/.rvm/gems/ruby-2.1.6/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'

在gemfile中,我有条目：gem’mysql2′,’?> 0.3′

检查安装了哪个gem：

$gem list|grep mysql2

activerecord-mysql2-adapter (0.0.3)
mysql2 (0.4.3)

我该如何解决这个错误？