title: Mongodb find(), limit(), sort() are not working
body: <p>In my project I need to find the most recent document in collection. I created one but it dose not return anything and I don't where is the problem exactly. Can you help me? 
  Function:</p>
  
  <pre><code>DBManagerConnection.prototype.findDeviceLastDeviceActivity = function(id, callback){
  database.DeviceActivity.find({deviceId:id}).sort({deviceLogin:-1}).limit(1), function(err,       deviceid){
    if(err || !deviceid){ 
      console.log(err);
      callback(err, null);
    }else{
      console.log("Find: " + deviceid);
      callback(null, deviceid);
    }
  }
  }
  </code></pre>
  
  <p><strong>Update</strong>:
  Yup Yup I solved the problem as show bellow:</p>
  
  <pre><code>DBManagerConnection.prototype.findDeviceLastDeviceActivity = function(id, callback){
    database.DeviceActivity.find({deviceId:id}).sort({deviceLogin:-1}).limit(1).toArray(function(err, deviceid){
        if(err || !deviceid){ 
          console.log(err);
          callback(err, null);
        }else{
          deviceid.forEach(function(item){
          console.log("Find: ");
          console.dir(item);
          });
          callback(null, deviceid);
        }
    });
  }
  </code></pre>
  
  <p>I would welcome any suggestions to improve the function.</p>