Simple Expression is not working , solve it

Hi Team ,

solve it .

Sy-subrc is zero is i give values .

it should be <> 0 .

CHECK             ( F1 <> 'A' OR F1 <> 'B'  OR  F1 <> 'C')

                                  AND

    (  F2 <> 'N' AND  F3 <> ''  ) OR (  F2 <> 'Y' AND  F3 <> '1'  )   .