Is it not going through an ignition sequence at all?
electrical problem
failed ignition module
wires fell off
Is it going through a sequence and stopping before it lights?
gas pressure low
sensor dirty
http://www.heatpro.us/service/ignitor.htm
What kind of ignition system is in the unknown model? Spark or hot surface?
http://www.heatpro.us energy businessmen’s knowledge
Yes, you really have to find out the MAKE and MODEL to get good answers. There IS more than one machine made.