Oven Elements

I have a Whirlpool (Model: RDE2400P). It has a upper and lower oven. I have never really use it since we bought the house 12 years ago. We mainly use our portable oven. When I turned it on today, I noticed that the Top Elements work for both upper and lower ovens. However, the Bottom Elements (Bake) do not work for both upper and lower ovens. Do the Top Elements turn on first and preheat the ovens before the Bottom Elements (Bake) kick in? Or: * Is this wired incorrectly? * Bottom Elements are defected (which I doubt since both Bottom Elements?)"