[cferriolm]

Hola Juan Camilo, prueba asi:
PARAMETERS: p_file TYPE localfile,
p_rad1 RADIOBUTTON GROUP rad DEFAULT 'X' USER-COMMAND ucom,
p_rad2 RADIOBUTTON GROUP rad.

AT SELECTION-SCREEN OUTPUT.
LOOP AT SCREEN.
IF p_rad1 = ' '.
p_rad2 = 'X'.
MODIFY SCREEN.
ENDIF.
ENDLOOP.

AT SELECTION-SCREEN ON VALUE-REQUEST FOR p_file.

IF p_rad1 = 'X'.
CALL FUNCTION 'F4_FILENAME'
EXPORTING
program_name = syst-cprog
dynpro_number = syst-dynnr
field_name = ' '
IMPORTING
file_name = p_file.
ELSE.
CALL FUNCTION 'F4_FILENAME_SERVER'
EXPORTING
pfad = '\\hph3\sapmnt\trans'
IMPORTING
file_name = p_file
EXCEPTIONS
no_file_on_server = 1
OTHERS = 2.
ENDIF.