problem with $conf['i18n_variables'] i have installed i18n module and added this lines to setting.php and empty cache to translate slogan and contact form information and  ... 
but it doesnt affect site and values dont add to i18n_variable table.

$conf['i18n_variables'] = array(
        'site_name',
        'site_slogan',
        'site_mission',
        'site_footer',
        'anonymous',
        'user_registration_help',
        'user_mail_welcome_subject',
        'user_mail_welcome_body',
        'user_mail_approval_subject',
        'user_mail_approval_body',
        'user_mail_pass_subject',
        'user_mail_pass_body',
        'contact_form_information'
    );


do you have any suggestion to solve this problem?
You need to actually go to the page in the admin that updates the variable and edit it from the non-default language url.

For example, with site name, if you have one other language with 'es' as a path prefix you would go to 'http://example.com/es/admin/settings/site-information' and change the site name. Once you do that in another language it will create the variable in the i18n_variable table.

You will know you are on the right track when the element you want to update in the admin says "This is a multilingual variable"