What is the correct way to fix bundler not finding compatible versions

I have an old rails 3 application which I want to update to rails 4 at the moment. I removed the Gemfile.lock manually and changed the Gemfile to require rails in version "4.0.0" before running a fresh "bundle install". I was getting several messages that bundler was not able to find compatible versions.

I am using ruby 2.0.0 here installed with rvm on a linux system.

I installed rails 4.0.0 manually using

gem install rails -v 4.0.0

And then I tried again with

bundle install

This is one example of the messages that pop up:

Bundler could not find compatible versions for gem "activerecord":
  In Gemfile:
    activerecord-import (~> 0.4.1) was resolved to 0.4.1, which depends on
      activerecord (>= 3.0)

    authlogic (~> 3.3.0) was resolved to 3.3.0, which depends on
      activerecord (>= 3.2)

    delayed_job_active_record (~> 4.0.0) was resolved to 4.0.3, which depends on
      activerecord (>= 3.0, < 5.0)

    rails (= 4.0.0) was resolved to 4.0.0, which depends on
      activerecord (= 4.0.0)

Due to the manual install of rails 4 I have activerecord in version 4.0.0 in my gems available. Why does it come up with that message? From my interpretation of the listed activerecord versions the dependency should be fulfilled with version 4.0.0? It is in the listed range between 3.0 and less than 5.