new atwood 7900-11 furnace help

[hgut]

hi, just installed all new gas lines, regulator,stove,gas-electric refridgerator,water heater and a atwood 7900-11 furnace. Problem is when I turn the thermostat up the blower comes on it trys to light 3 times and then goes to fault, (3 light flash) maybe it will fire up 1 out of 10 times, I pulled the ignighter out the gap looks good and the spark does too, when I ran wires to the thermostat I went with the white wire out of the furnace and a positive, is this the correct way? I cant figure out why it will not fire up each time I call for heat. All my other new appliances work great. thanks for any advice.