Punter on Defense unit

I have the Detroit Lions secondary and Yale Lary is listed as "FS, Punter". But when I go to set my lineup his name does not appear as a punter option.........How do I activate him?

Late response but I don't think you can. You have to leave the punter spot open in your lineup and see if HAL uses Lary there. Same for defensive backs eligible as kick returners.