The Issue is now found and solved and I just tested it on your test-site.
Ogone added silently a new optional parameter in its SHA-OUT signature for the payment service provider!
I have now updated the SHA-OUT parameters list, and it now works well on your test site.
Nightly CBSubs build which will be available by tomorrow, contains the fix too.
I am personally deeply sorry for having had this delay in finding and fixing this change that Ogone made without informing us.
I have extended your paid membership here free of charge so that you have enough time to get everything working.
Which other issues do you have woth the Ogone plugin ? I will personally have much more time starting in January, so that we should be able to fix any bugs that you might have encountered.
We are using it on this site without any issues, but you don't have the same PSP.
#6402