Issue when running jirb

Whenever I run jirb, I get the following:

root@nycserv-deva-app1nim:/usr/local/bin/ruby_inst2/jruby-1.1.2/bin>jirb
jirb:16:in `require’: no such file to load – irb (LoadError)
from jirb:16

Has anyone seen that error before?
Param