SAP Note 10956 - Internal error FZ326 : Document balance not zero .

Symptom

The following error message can appear with the SAPF110 payment
program: E326 Internal error: doc.balance not zero / comp.code & vendor &customer &.

Cause and prerequisites

Credit memos and invoices are to be paid together. Due
to different exchange rates in the document, the combination
can occur that the balance in foreign currency and the
balance in local currency have different +/- signs which leads
to the above error.
For example,
Invoice 1000 USD 1900 DM (rate 1.9)
Credit memo 990 USD 1980 DM (rate 2.0)

Solution
You have the following options:
1. You pay the items separately.
2. A new credit memo at the exchange rate of the invoice is
posted to the business partner account, and at the same
time the old credit memo cleared. The new credit memo
can then be paid together with the invoice.
In the above example:
New credit memo 990 USD 1881 DEM (rate 1.9)
(When clearing, the old exchange rate difference of 99 DEM
which emerges is posted automatically) .

Key word: FZ326