Program error: Entry incomplete when calling function module

What causes this issue?

The function module 'FIAA_T093C_DATUM_CHECK' was called up with
incomplete paramters.
Either the parameter I_DATUM or the parameter I_PERIV was not entered.
You have to enter both parameters.

System Response

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

How to fix this error?

Inform your system specialist.

Error message extract from SAP system. Copyright SAP SE.