Program & has no selection screen or variants

What causes this issue?

You asked the system to display the variants of an ABAP/4 program or
you wish to maintain variants for the program. However, the
program does not offer a selection screen to the user. The program
therefore has no variants and no variants can be defined for the
program.

System Response

No action taken.

How to fix this error?

Error message extract from SAP system. Copyright SAP SE.