Billing due list

Hi all

I need to customize Billing in CRM. I made these customizing:
1. Define Billing Relevance of Item Categories
2. Define Billing Types
3. Define Billing Item Categories
4. Assign Item Categories
5. Define Item Categories - Transaction-Related Billing After Completion

But when I execute Billing due list there are no any records. I don't have integration with ERP and don't need it. But on the Sales order I have errors:
-Error in system ERP___ while copying the document
-An error occurred in system ERP___ during account assignment

Maybe Billing due list is empty because there are errors on the order? If yes - how to switch off this integration? Also I can see error BDocs BUS_TRANS_MSG. But I somehow customized it and now BUS_TRANS_MSG are completed.

So questions are:
1. Why Billing due list can be empty?
2. If it because integration errors - how to switch it off?

Thank you.