Alternating option in Display settings ( WEB DYNPRO ALV )

Hi Freinds

in My Webdynpro ALV,  in Settings ( Display Settings tab ), In Table design , when i select ALTERNATING options, the alv report is not displaying in zebra format,  can u please help me , if i select ALTERNATING option, the output should  be display in ZEBRA  format

Thanks and regards

Srini Kumar