2431760 - FTR_EDIT: it is not possible to reverse a posted flow in the Cash Flow tab

You want to reverse a single flow in an OTC derivative or Money Market Transaction. In the Cash Flow tabstrip of the transaction the reversal functionality for a single flow is greyed out.
 

SAP R/3
SAP R/3 Enterprise 4.7
SAP ERP Central Component
SAP ERP
SAP enhancement package for SAP ERP
SAP enhancement package for SAP ERP, version for SAP HANA
SAP S/4HANA Finance
SAP S/4HANA

field modification, FMOD, reversal, cashflow, OTC, commodity, swap, forward, Feldstatus, Finanzstrom, ausgegraut, Storno, Bewegung , KBA , FIN-FSCM-TRM-TM , Transaction Manager , Problem