Dear,
I think,If you see below screen shot then you can understand what you have done mistake .If you maintain Completion Rule E then you can not maintain Billing Relevance .Completion rule E can work in two situations only .You can see in what situations ,system will accept theses two options .
I think,in your TAN Item category ,doesnt have any value in the Field "Billing relevance ".I dont how system has allowed you to create a Billing in VF01 without Billing relevance .One more thing is ,Have you maintained requirement Type 2 in your pricing procedure for any condition type .
What is Contract doc type and Sales doc type ?
Have you maintained Reason for rejection in any where ?
Please share the VTAA screen shots .
Thanks,
Naren