Authorization check

What is wrong? Even if the parameter pa_car is set to a person who does not exist, the system does not write "Not authority". Why???

AT SELECTION-SCREEN.

AUTHORITY-CHECK OBJECT 'S_CARRID'

ID 'CARRID' FIELD pa_car

ID 'ACTVT' FIELD '03'.

IF sy-subrc <> 0.

MESSAGE i398(00) with 'Not authority!'.

ENDIF.