If the draft inducer fan comes on but the ignitor coils don't then it must have something to do with the pressure switch at the vent. Find that switch and put a continuity tester across the 2 terminals as it try's to start up and see if the switch closes, if it doesn't than it could be the switch if it does than it might be the connection.
I do install furnaces and A/C for a living so I'll try and answer any questions to help you resolve your no heat issue.
Good luck
