my wall heater wouldn't kick on so i checked the pilot. it was out but was able to light the pilot when i turned the starter know from "on" to pilot but it won't stay lit when i turn it to on. directions say let in burn for 30 seconds but i have tried it for over 2 minutes as well as shut it down for 10 minutes and tried to start it. is this an easy fix or do i need a pro??