Drupal Search Services Not Working

I’m using this post to add search functionality to my DrupalGap app: http://docs.drupalgap.org/7/Services/Search_Services 

However, I cannot find search_node or search_user under admin/structure/services/list/drupalgap/resources to check the retrieve box and whenever I try running a search after inserting the search block in the home page, I get the following error: “Failed to load resource: the server responded with a status of 404 (Not found : Could not find resource search_node.)”

I’m currently running Drupal 7.59 and I already have all the dependencies installed. Any ideas on what the problem could be?

Drupal version: 


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