Logstash-syslog-output install issues

[jyork]

I ran the following command:

sudo gem install logstash-output-syslog

Get the errors below:
ERROR: Could not find a valid gem 'logstash-core-plugin-api' (<= 2.99, >= 1.60) in any repository
ERROR: Possible alternatives: ph-logstash-core-plugin-api, logstash-codec-line, logstash-codec-plain, logstash-codec-fluent, logstash-codec-lineeof

I tried to install the possible alternatives it suggested, but got the same error.
I'm not sure how to fix this issue.
Any help is much appreciated.

[jyork]

Another member of my team figured out how to make this work correctly.
Using the command below:
/usr/share/logstash# jruby -S gem install logstash-output-syslog
Fetching: logstash-codec-plain-3.0.3.gem (100%)
Successfully installed logstash-codec-plain-3.0.3
Fetching: logstash-output-syslog-3.0.2.gem (100%)
Successfully installed logstash-output-syslog-3.0.2
2 gems installed