Modify Asset order sales

While reviewing and posting invoices, I went in to Post and Print, but then noticed that the document date was incorrect. I changed the date and then tried to post the invoice, but received the error message below.

The Asset Order Sales already exists

What is the course of action i should take to resolve this problem

Did you tried to post the sales order once ?

There is still a bug in the system, that the order no. gets stored in the header.

To resolve the same you need to manually delete the no. stored in the header and the post the order.