It sounds like you have an intermittent pilot ignition system. This is where you would hear a ticking noise and then a piolot lights and then a few minutes later the main burners ignite. IS this the system you have or is there an orange glow and then the burners ignite? this would be a hot surface ignition system. If you have the first system the - Intermitent ignition system and the pilot lights but the main burners do not-there are two main possibilities.
1ST the Three wire pilot is bad and needs replacement or the main gas valve itself has aproblem and needs replacement. Either way you need a service tech to determine this. Good luck...PS what city are you in? If you are in the Sacramento California area or the Oakland Bay area I might be able to help you.