If your glow stick (hot surface igniter) isnt hot enough to reach the flashpoint of the gas, it won't light.
You might have a faulty Hot surface igniter.
you have to check your gas pressures and make sure that you are getting 3.5" WC in the manifold side of the gas valve.
if you have had recent work done on the gas line, ie; range installed, furnace work, gas line relocation, you might want to bleed the gas line.
If not, then check the pressures.... if they are good, look into replacing the HSI.
I hope I was of some assistance.