Missing source file (valid in console, errors when accessed online)

Environment info:

Ruby 1.9.1-p376
Rails 2.3.5
Apache2 with Passenger mod

I installed the nokogiri gem like I would any other gem however when I
require it at the top of my controller and access it through apache, I
get an error saying "Missing source file" and it lists nokogiri. I
have other gems required at the top and when I don't have nokogiri
required everything works fine.

Also when I try requiring nokogiri in the console I don't get that
error.

I was told that this is a Rails issue so any help would be appreciated.