White schreen after external payment call

We are using the latest Hikashop 2.0.0 in Joomla! 2.5.8 and have added "IDEAL" as payment method with the payment extension from ideal-checkout ( www.ideal-checkout.nl ).
But now after getting the status from iDeal we always get a white screen.
Turning on debug mode shows this info. I See a message invalid_status.. Is this a Hikashop problem or is it an ideal-checkout problem?
The website is www.mooicv.nl

Kind regards, Evert

Debug console:
__default
session.counter ⇒ 28
session.timer.start ⇒ 1352925954
session.timer.last ⇒ 1352927633
session.timer.now ⇒ 1352927946
session.client.browser ⇒ Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0
registry ⇒ {"com_hikashop":{"ssl_redirect":0,"zone_id":"150","vote":{"list_limit":"30"},"cart_id":19,"shipping_method":0,"shipping_id":0,"shipping_data":0,"cart_new":"0","payment_method":"idealcheckoutideal","payment_id":3,"payment_data":{"payment_id":"3","payment_name":"iDEAL","payment_description":"

Betalen met iDEAL<\/p>","payment_images":"","payment_params":{"payment_currency":"1","payment_percentage":"0","invalid_status":"cancelled","pending_status":"created","verified_status":"confirmed"},"payment_type":"idealcheckoutideal","payment_zone_namekey":"","payment_access":"all","payment_shipping_methods":"manual_1","payment_currency":",1,","payment_price":0,"extension_id":"10093","name":"iDEAL Checkout - iDEAL","type":"plugin","element":"idealcheckoutideal","folder":"hikashoppayment","client_id":"0","enabled":"1","access":"1","protected":"0","manifest_cache":"","params":"","custom_data":"","system_data":"","checked_out":"0","checked_out_time":"0000-00-00 00:00:00","ordering":"37","state":"0"},"checkout_fields_ok":0,"order_id":30},"users":{"login":{"form":{"data":[],"return":"http:\/\/www.mooicv.nl\/"}}}}