SAPscript form not entered

What causes this issue?

The following form is printed for the chosen payment method:
CASE &V1&
WHEN '1'
Payment medium
WHEN '2'
Additional payment media
WHEN '3'
Sheet accompanying disk
WHEN '4'
EDI accompanying sheet
ENDCASE
You have not specified which SAPscript form is to be used for this
payment method.

System Response

The form is not printed.

How to fix this error?

Define a suitable SAPscript form on the selection screen of the report
program <DS:REPN.SAPFKPY3>SAPFKPY3</> (or in a variant), or define the
form in <DS:TRAN.FQP4>Customizing</> (company code specifications for
the data medium format).

Error message extract from SAP system. Copyright SAP SE.