JotForm PHP API to update hidden question answer

Hi, we're using JotForm to create a conference registration page, which subsequently redirect to a custom payment gateway that processes customer's credit card.

Now we're writing a PHP script that updates the payment status field in JotForm (so it can be reflected in the Google Spreadsheet that the JotForm generates).

After reading the API docs, it seems that the function below does the trick:

$jotformAPI->editSubmission($submissionID, array("answers" => array("45" => "PAID")));

I have initialised $jotformAPI and $submissionId properly, but it doesn't seem to work. 45 is the question ID. Could you please help me fix it?

The form can be viewed at: http://form.jotform.co/form/52248776111859

And payment status is at the last question (hidden field), which needs to be updated by our PHP script to either Paid or Not Paid.

Thank you for contacting us.

As far as I know, only text fields can be integrated with API. However, to get the right answer on regards to integrating payment  fields, please contact api@jotform.com