No assignment of amount &1 &2 possible due to selection specifications

What causes this issue?

The named amount is to be assigned or posted on account. No receiving
contract account can be determined from the selection specifications.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Check the selection and enter further specifications for the payment
where appropriate.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.