Uninitialized constant Rails::Initializer::MemCache

I’ve installed just about every library/gem that I could find for
memcached/memcache, but everytime I attempt to run my application I get
this error:

Error message:
uninitialized constant Rails::Initializer::MemCache

Exception class:
NameError

My environment.rb has these lines:

require ‘memcache’
config.gem “memcache-client”, :lib => “memcache”

I have tried $ telnet localhost 11211 and memcached is definitely
running. Any ideas?

(I’m running Apache2/Passenger)