I have been setting up a SwipeStripe store and am trying to integrate the Paypal Express Checkout using the frankmullenger/silverstripe-payment-paypal.
I have followed the module installation instructions as indicated on github, however, when i go through the checkout process and click "Proceed to Pay", I am being thrown an error by the website which is stating:
[Notice] Undefined index: authentication
Line 33 in ..../payment-paypal/code/PayPalGateway.php
Which corresponds to the following line in the callAPI function;
$authentication = $config['authentication'];
It seems there is an error in retrieving the configuration of the API Details