It's a wax/oil finish you've been using. I don't know of any paint finishes that would work well with that. I know Tru-Oil goes over Dingotone from other's experiences, but all the spray finishes I know require clean, grease-free surfaces to work on. I'd suggest you either use Tru-Oil, or wait a month or so to see if the oils/waxes have then evaporated fully leaving only the stain behind and try spraying again.