SAP Message PSZ1021 - Form-based processing not possible

Diagnosis
The planning layout contains the transaction currency as a key column.You have also chosen the form-based input mode.
This constellation produces an unclear planning layout because thereare default entries in many of the lines. For this reason, it is notpermitted.

System Response
Processing stopped.

Procedure
Select the free input mode or use a planning layout which doesnot have transaction currency in the key column.