Error Message M8 534 when posting vendor invoice

Hello Guru's!

My client has a BSP application that the purchasers are using to approve and post vendor invoices.

When the user is approving the invoice, we have a WF setup to automatically post the invoice to FI.

We're using standard SAP functionality. BUS2081, method PreliminaryPost.

First, this method is reading the preliminary invoice using method MRM_INVOIC_READ, then it goes on to try to post the invoice, using MRM_PARKED_INVOICE_POST.

In about 50% of the approvals, the invoice is posted to FI but the other 50% kicks out with a message M8 534 - Balance not zero: & debits: & credits: &.

Then the system is setup to generate a new WI in order to post the invoice manually.

The issue, is that before the method PreliminaryPost is carried out, there is a check online to make sure the document ís OK.

So, i know that there is no balance on the document, and it should be ok to post.

This issue arised recently after my client went through an upgrade from ECC 5 to ECC 6.

I have seearched OSS for notes, adn related notes are implemented.

Any thoughts on this

Thank you for sharing your wisdom.

Lars