locale() called without arguments

I installed the 5.x-1.0 version, and it didnt work. The translate box on the footer doesnt appear, and I get this warning on all pages:

warning: Missing argument 1 for locale(), called in /var/www/html/manal/5.1/sites/all/modules/l10n_client/l10n_client.module on line 73 and defined in /var/www/html/manal/5.1/modules/locale/locale.module on line 163.

the locale() function is being called without arguments to get a list of all translatable strings, according to the drupal api this method works on drupal 6 but doesnt work on drupal 5