Hi
Try this example code done using selection screen comment and radio button in PBO
SELECTION-SCREEN BEGIN OF BLOCK b1.
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN COMMENT 1(10) t1.
PARAMETERS p1 TYPE matnr.
SELECTION-SCREEN END OF LINE.
PARAMETERS r1 RADIOBUTTON GROUP g1 USER-COMMAND M1.
PARAMETERS r2 RADIOBUTTON GROUP g1 DEFAULT 'X'.
SELECTION-SCREEN END OF BLOCK b1.
AT SELECTION-SCREEN OUTPUT.
IF r1 = 'X'.
t1 = 'MATNR'.
ELSEIF R2 = 'X'.
t1 = 'MATERIAL'.
ENDIF.
Hope this helps.