Heater won't work - am I missing something? HELP

You probably had some air in the line. Try turning the furnace off, running the stove for a couple min, and then turning the furnace back on. It may take a few cycles to work out any air and get ignition.

It is possible that the DSI for the furnace is bad, or that the thermocouple is bad. Do you hear any attempts at ignition or ignition?

Stand by the exhaust outside when it starts and see if it gets hot and then cold. Hot will be HOT so do not burn yourself.