There is a flow still to be posted on &1

What causes this issue?

A profit and loss realization for an interest rate can only be carried
out when all flows released for posting are posted. For this
transaction there is at least one flow still to be posted.

System Response

The realization is not carried out.

How to fix this error?

Post all the flows to be posted for the transaction and then carry out
the realization.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.