Session data not saved in the session file although file created (using :p_store)

Hi all,

I am new to Rails. I want to test some things with sessions. But I
simply cannot make them work. I am using this in the environment.rb
file:

config.action_controller.session_store = :p_store
config.action_controller.session = {
    :tmpdir => "#{RAILS_ROOT}/tmp/sessions/",
    :session_key => '_tests_session',
    :secret =>
'f23e19a920da3ccb0a128f24d97a85e36618b7e6dc920167febe16f24ca89462d5bf83598d87d2d842c1fd273bb7df98b23ee6291c8fe6bfe8fdcf973929b645'
}

The file "ruby_sess.d38fcbeda549de99" is created in my