Water heater

I know my water heater used to work on gas but now i'm having problems with it.As i understand the switch in with the water heater needs to be on so it will work on gas.The water heater has electronic ignition instead of a pilot light and i'm getting gas to the valve but i can't see or hear any spark.Either i'm not doing something right or something has happened to it.It has worked in the past but we havn't used it on gas this year.When i was checking to see if it worked on gas the water was cold.
We have been using the electric element but i want to make sure it will work on gas.
Thanks for any help.

Happy Campers,The switch on the tank has to be on for electric operation along with the light switch with the RED toggle on the control panel. To operate on gas you have to turn on the switch to the right of the water pump switch, the little dot will stay on until it lights. Hope this helps, JON

John, the little rocker switch inside the heater panel has no effect on operating the heater on gas. The usual problems after operating on gas for a while are air in the lp piping or spider webs in the air orifice/burner tube. Try turning off the switch for the water heater that is on your monitor panel. Have someone near the water heater and turn the switch back on. They should hear the ignitor trying to light the heater. If you can hear the ignitor and the burner tube is clear, you might have air in the lines or maybe out of LP??

When trying to light the electric ignite gas appliances for the first time after a shutdown the air needs to be let out of the lines. I have found in my Bh as well with all my previous campers, the easiest way to do this is to open a stove burner and keep trying to light it with a match/lighter until it lights. Burn all of the burners for a few minutes then shut them down. That should have gotten the air out of the lines and then the refrig and water heater will generally light on the first try.