Error when adding hook_xmlsitemap_links, to the settings.php

Hello,

I want the sitemap to recognize pathauto or alias url's.

when I try to add a hook, custom_url_rewrite or the hook_xmlsitemap_links, to the settings.php I receive this error:

warning: Missing argument 4 for custom_url_rewrite() in /home/ratrodde/public_html/rat/rattest/sites/default/settings.php on line 166.

Could you tell me if I need to add something else to make the code valid? I am copy pasting the code as I see it to the bottom of the settings.php file.

Thank You,
Lorraine