As far as I know you cannot create a ceiling by picking the faces of a mass. I often have this problem and the only workaround I have found is to pick the surfaces of the mass to create a wall/floor/roof, whatever works, and then use either unhosted lights or some of the workplane based lights that came with the recent releases of Revit (e.g. the LED downlight).
The ceiling hosted lights (i.e. most that still ship in the default library) will never work using this approach, but it's not that hard to make unhosted or workplane based versions of the ones you need then you can place them anywhere, even when you don't have a ceiling (set to the ceiling category). It's still gonna mess up your schedules, takeoffs etc. though if you need your ceilings for those things
