aws-graphs problems

ouychai@ouychai-HP-Notebook:~$ sudo aws-graph draw -c config.yml -o output.png
[sudo] password for ouychai:
/var/lib/gems/2.2.0/gems/aws-graph-0.0.5/lib/aws-graph.rb:229:in `load': uninitialized constant AwsGraph::CLI::YAML (NameError)
	from /var/lib/gems/2.2.0/gems/aws-graph-0.0.5/lib/aws-graph.rb:16:in `draw'
	from /var/lib/gems/2.2.0/gems/thor-0.19.4/lib/thor/command.rb:27:in `run'
	from /var/lib/gems/2.2.0/gems/thor-0.19.4/lib/thor/invocation.rb:126:in `invoke_command'
	from /var/lib/gems/2.2.0/gems/thor-0.19.4/lib/thor.rb:369:in `dispatch'
	from /var/lib/gems/2.2.0/gems/thor-0.19.4/lib/thor/base.rb:444:in `start'
	from /var/lib/gems/2.2.0/gems/aws-graph-0.0.5/bin/aws-graph:5:in `<top (required)>'
	from /usr/local/bin/aws-graph:23:in `load'
	from /usr/local/bin/aws-graph:23:in `<main>'
ouychai@ouychai-HP-Notebook:~$