SQL driver won't load

Hello.

In order to integrate with a customer's MS SQL back-end system, I'm
trying to employ the technique described here:
http://pullmonkey.com/2008/4/21/ruby-on-rails-multiple-database-connections/

I get this:

Please install the sqlserver adapter: `gem install activerecord-
sqlserver-adapter` (can't activate activerecord (= 1.15.6, runtime)
for [], already activated activerecord-2.3.5 for ["rails-2.3.5"])

Any ideas?

--Ray