If you are unable to continue to the Pay Now step of the wizard, then this means you are not using a secure form.
- Check the URL being used starts with"httpS://"(Note the "S" part). It has been the case with some organisations that when they've added the form to their website, they have missed this part.
- That the URL being used has ".secure.force.com" in it. Eg."https://xxxxxx.secure.force.com/"For more on this, check the setup procedure: How to connect your new site to your Merchant Facility.
- Make sure the Secure URL (points 1 and 2) is entered on the Merchant Facility "Site URL" field