findOne has no callback with MongoDB and node.js

I'm using MongoDB 2.0.6 with node.js and the mongodb-native module. I'm trying to create a database of different social media items and currently have tweets properly populating my database. I'd like to add a function that gets the most recent tweet ID (not mongo ID but a field called 'api_id') and returns it for use in an API call.

I followed this great tutorial as the base for what I have but the findOne function seems to never hit its callback. I tried using findOne with the native Mongo ID serialization as well but no luck. I'm going to try a workaround suggested here for Mongo 1 but I don't think it will work. Any help would be appreciated.

// Find one by given criteria
updateSocial.prototype.findByCrit = function(crit, callback) {
    this.getCollection(function(error, social_collection) {
      if( error ) callback(error)
      else {
        social_collection.findOne({api_type: crit}, function(error, result) {
            if( error )
                callback(error)
            else {
                callback(null, result);
            }
        });
      }
    });
};