Could not load the 'chef-solo' provisioner from the load path

I have freshly installed ChefDK on my workstation, downloaded the starter kit and modified .kitchen.yml to follows:

---
driver:
  name: opennebula
  opennebula_endpoint: http://10.1.1.1/zonea
  oneauth_file: /home/local/.one/one_auth
  template_name: CHEF-TESTVM
  vm_hostname: CHEF-TESTVM-FRONT-END
  public_key_path: /home/local/.ssh/id_rsa.pub
  username: root
  memory: 4096
  require_chef_omnibus: false
  user_variables:
    FILEHOME: http://10.1.1.2/~dev/repo/

provisioner:
  name: chef-solo
  environments_path: /home/local/chef-repo/cookbooks/init/environments/
  role_path: /home/local/chef-repo/cookbooks/init/roles/

platforms:
  - name: ubuntu-12.04

suites:
  - name: default
    provisioner:
      solo_rb:
        environment: dev
    run_list:
      - recipe[wfe]
      - role[common]
    attributes:

Kitchen is provided with the Chef. (use the built-in kitchen/gem/bundle etc)

And I ran kitchen test it gives the following message:

>>>>>> ------Exception-------
>>>>>> Class: Kitchen::ClientError
>>>>>> Message: Could not load the 'chef-solo' provisioner from the load path. Please ensure that your provisioner is installed as a gem or included in your Gemfile if using Bundler.
>>>>>> ----------------------

which chef-solo returns /opt/chefdk/bin/chef-solo

If I change chef-solo to chef-zero, it is omitting the same error during a kitchen diagnose:

exception: "#<Kitchen::ClientError: Could not load the 'chef-zero' provisioner
  from the load path. Please ensure that your provisioner is installed as a gem
  or included in your Gemfile if using Bundler.>"

I have already installed kitchen-opennebula gem, but I suspect this problem is nothing related to that.

What is going on?

Solution

I found out that it was a typo:

chef-solo should be chef_solo in the yml.

Solved.

I had another similar problem that blocked me some time try to find out why (data_bag_path vs data_bags_path, it should have an 's')