Hello, I am having some template related issue resulting in

Your order's details have changed. Please review the current values and re-submit.

Fresh zencart 1.5.6.b with only CEON URI installed and the OPC 2.2.2.

When I test it with the responsive template OPC seems to work nicely, but when I change to my template GOODWIN something goes wrong and

Message Your order's details have changed. Please review the current values and re-submit. appears.

I am using only cod as payment and store pickup delivery.

What may cause this error? It is quite possible something from the template part but where to look for?

Kind regards.