Fatal error: Call to undefined function variable_children()

I am upgrading the installation, the cache has been cleared. The latest version of variable 2.0 and i18n are both present in /modules.

I get the following error message:
An AJAX HTTP error occurred. HTTP Result Code: 200 Debugging information follows. Path: http://www.example.com/update.php?op=selection&token=66hdsDA5C-aFADnXVm7... StatusText: OK ResponseText: Fatal error: Call to undefined function variable_children() in /home/user/public_html/example.com/sites/all/modules/i18n/i18n_variable/i18n_variable.install on line 70