BackOffice: access denied


I have a problem when accessing the backoffice of Omeka but the homepage of the front office works fine.

- ubuntu 14.4 installed via VMware Player on windows7
- Omeka 2.3
- URL Access Server: http://localhost/Omeka/admin/users/login

Actions already completed:
- uncommented in .htaccess, RewriteBase and adding RewriteBase / Omeka
- uncommented SetEnv APPLICATION_ENV in .htaccess file (file in omeka directory)
- remove the "/" after admin in the URL
-In the 000-default.conf file etc / apache2 / sites-available, I have "AllowOverride All".
- Reinstalling Omeka
- set the writing problem Omeka with chmod-R 777 / var / www / html

I think it is related to Apache mod_rewrite but impossible to correct the problem.

Do you have a solution because I am completely lost?

Thank you in advance,