rss fluent in error with td-agent v2

[sgreco2002]

Hi,
i'm trying to use your rss plugin, but seems doesn't work at all.
steps to reproduce are:

1. install td-agent v2
2. install plugin with command td-agent-gem install fluent-plugin-rss
3. add in td-agent.conf

<source>
	@type rss
	tag rss.nytimes                                     
	url http://example.com/input-your-rss-feed-here.rdf 
	interval 10m                                        
	attrs date, title                                   
</source>

start td-agent
after start, the service crash with error:

/opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluent-plugin-rss-0.0.1/lib/fluent/plugin/in_rss.rb:4:in `<module:Fluent>': uninitialized constant Fluent::Input (NameError)
        from /opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluent-plugin-rss-0.0.1/lib/fluent/plugin/in_rss.rb:3:in `<top (required)>'
        from /opt/td-agent/embedded/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from /opt/td-agent/embedded/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from /opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluentd-1.1.3/lib/fluent/registry.rb:102:in `block in search'
        from /opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluentd-1.1.3/lib/fluent/registry.rb:99:in `each'
        from /opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluentd-1.1.3/lib/fluent/registry.rb:99:in `search'
        from /opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluentd-1.1.3/lib/fluent/registry.rb:44:in `lookup'
        from /opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluentd-1.1.3/lib/fluent/plugin.rb:146:in `new_impl'
        from /opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluentd-1.1.3/lib/fluent/plugin.rb:100:in `new_input'
        from /opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluentd-1.1.3/lib/fluent/root_agent.rb:277:in `add_source'
        from /opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluentd-1.1.3/lib/fluent/root_agent.rb:122:in `block in configure'
        from /opt/td-agent/embedded/lib/ruby/gems/2.1.0/gems/fluentd-1.1.3/lib/fluent/root_agent.rb:118:in `each'

could you please help me?