Cannot turn on Oven

Question

I have a Westinghouse Multifunction Freestyle 476 Gas fired oven. I have mabnaged to turn the oven on a few times but cant figure out why it dosent always work. I turn the oven setting to "Bake" and turn the temp knowb to 200, the lights come on automatically after afew seconds to indicate that it has powered up and the gas pilot comes on but the oven's main gas dosnet come on. I have triesd different combinations of the cooking button (the veseel icon with heat waves) and the timer button; setting times for both, 1 of them seperately and all the combiantiosn thereof but to no avail.. I have also tried looking for manuals but havent been successful. Please help!!!