SAP Message 69155 - Partner + payment method must be allocated to the conditn (see long text)

Diagnosis
Error in payment method selection:
You must allocate a payment method with
- outgoing payments and
- single payment
to the condition, since the condition generates flows which are markedas payments to third parties.

Procedure
Select a corresponding partner. The payment method must be allocated tothe partner in the current company code. If this is not the case, youmust first allocate the payment method to this partner in partnermaintenance.