I can't tell what kind of appliance you're talking about.... but, here's what I know.. This "lever" you're talking of kind of stumps me, but try, after the gas lights, to hold the lever in the position you had when you lit the flame. Hold it on for about a minute... then release it... and see if the flame will remain going. If you can't keep the flame going "no matter what", you probably need to clean or replace the flame sensor.