Search files API calling function in Directories sub-module

I am trying to use the Search Files API with another module that is not part of Search Files. So I enabled Search Files API but neither of the sub-modules.

When I try to visit the main Search Files API menu page (path admin/settings/search_files), I get the following error:

Fatal error: Call to undefined function search_files_variable_get_directoryrescanage() in /opt/www/drupal-6.13/sites/all/modules/search_files/search_files.module on line 83

The problem is that this function is in module search_files_direcotries, not in search_files. So it shouldn't be called from the Search Files API page.