Add new field or meta to admin notification email

I am trying to add the result of an third-party API lookup to the Admin Notification email. I've tried a few different ways and none are working. For these I depended upon hooking into 'gform_entry_created' so that the entry exists already when I'm trying to add my data.

- Add a custom entry meta field to the entry, then display that meta field in the notification email
- Add a hidden field (named: "Reservation Guid") and update its $entry[field_id] value to the value of my third-party API result

With the custom entry meta method, it doesn't seem like my meta is ever attached to the entry, it doesn't exist in the email.

With the hidden field method, it doesn't seem like setting the value of $entry['23'] to any value actually changes the value on the entry object.

Here is my code snippet:

http://pastebin.com/GcU3X8rg

using GF version 1.6.3.3.2

Hi Gravity Forms,

I'll restate my question in the hopes I get a response:

I would like to add the value of an API call to the admin notification email, only after a user has successfully submitted a valid form. The API call is currently being made user the 'gform_entry_created' hook. (btw, when I used 'gform_entry_created_2' the hook never fired)

Is there a way to do this?

http://pastebin.com/GcU3X8rg