@ Brent: thank you. You are right, I used an older file. The only difference is the deletion of the icon column. So I have changed the archive.
@ oberheimer: this bug looks like a bad copy and paste of a mod to a genuine zen cart file. Try to find what you have modified in the checkout files and redo it carefully. It is a classical mistake. You should try to find better advice on this matter in other sections of this forum.