Rails 3.1 and SQLite3

I am getting this message when running my tests against RoR-3.1

`establish_connection': Please install the sqlite3 adapter: `gem
install activerecord-sqlite3-adapter` (sqlite3 is not part of the
bundle. Add it to Gemfile.)

However, I already have this in my Gemfile and this works fine with

gem 'sqlite3-ruby', "= 1.2.5"

changing this line to

gem 'sqlite3-ruby', "= 1.2.5" , :require => 'sqlite3'

and running bundle install does not resolved the problem.

The host system is running CentOS-5.7 and the distribution ships with
SQLite-3.3.6. The most recent versions of sqlite3-ruby do not compile
against this version of SQLite3 but this is the most recent version of
SQLite3 that we can obtain authorized packages for. The author of
sqlite3-ruby has written that sqlite3-ruby does not, and will not,
support SQLite-3.3 after version 1.2.5 . We are therefore constrained
to use sqlite3-ruby 1.2.5.

How can I fix this problem?