punchout cart cXml error

I am setting up supplier side of a cxml punchout site and getting errors at buyer/hub. I am sending the orderMessage but an error occurs. Please see the attachment. I am currently asking for the bid for the solution. Future scope: I will give the next phase of the development by hourly rates or a fixed price. Once I am confident, I may simply give the rest of the project to you at a fixed project price. Please bid ONLY IF you have worked with punchout carts and can solve this problem. Pun…