Sylius: configure of MultiSafepay

Question

I trying to configure MultiSafepay in Sylius 0.14. When using omnipay_direct or omnipay_offsite in the config.yml I get this error (The payment details have been filled in: Name, Card number etc):

The transactionId parameter is required

Is the transactionId not created automatically i.e the order_ID or number ? Or do I have to extend it somewhere to set it ?

Ideally I'd like to fetch the list of available payment methods and redirect the user.

Main question: Could someone get me on the right way to do this ? I'm new to Sylius and also rather new to Symfony2.

my config.yml:

sylius_payment:
    gateways:
        multisafepay: MultiSafepay

payum:
    payments:
        multisafepay:
            omnipay_direct:
                type: MultiSafepay
                options:
                    accountId: xxxxx
                    siteId: xxxx
                    siteCode: xxxx
                    testMode: true

In core sylius.:

sylius_payment:
    classes:
        payment:
            model: Sylius\Component\Core\Model\Payment
            controller: Sylius\Bundle\CoreBundle\Controller\PaymentController

...