First of all..you should already have at least a couple of extra glow plugs for the engine.I believe a 40 OS come with that plane. That takes an A3 plug. They're not very expensive. Next, use you glow plug wrench (you gotta have that) and remove the glow plug. You have to confirm that the glow plug and glow plug igniter are working. Hold the glow plug in something like pliers (grip just enough to hold) or a heavy fire resistant glove. They heat up in a hurry. Connect the igniter and you should see an obvious glow of the filament in the inside center of the plug. If not one or both of the 2 are not working. Try connecting the glow starter to a brand new plug to rule out the plug. Stay connected just long enough to confirm glow. If still no heat...your starter isn't working. Look into fixing that or getting another starter.

When priming the engine, do so according to the manual procedure. Don't expect to see a line full of fuel between the fuel outlet and the carb while priming.. Start with the needle valve opened about 1 1/2 turns. Make a small mark on the top of it with a marker (Sharpie) so you know how much you've turned it and you can close it up after starting to adjust to proper run setting. With the throttle opened a bit (without the glow starter connected!!!!!) plug the carb opening with a finger and give several flips or rotate the prop with a frm hand motion thru several compression strokes counterclockwise...from the front view. Get a trusted friend to securely hold the plane. Connect the glow starter. Then try. STAY CLEAR OF THE SPINNING PROP.
Good luck,