neff u1421 double oven?

Hi i have just brought a secondhand neff oven and wired this up to a 13amp plug to see if its working ok...but only the top oven and grill seem to be working the bottom oven doesnt seem to have any power going to it?will this have to be hard wired before this works or is there a fault with the oven that someone might be aware of
can anyone help
regards jas