Ruby issue while configuring sensu checks

I have sensu server and sensu-client Installed on one machine (centos)
and installed the the plugins through gem.

Everything was good when I run the check_ping.rb from the command line,
but When I configure the same check in /etc/sensu/conf.d/ and check in
the UI I am getting this ruby issue;

gem install sensu-plugins-network-checks

I have ruby installed of 1.9.3 version

and configured EMBEDDED_RUBY=true

when I check the UI the below is the error I am facing

`require': cannot load such file -- net/ping (LoadError)
Sensu::Plugin::CLI: ["Not implemented! You should override