i have a tappan upflow furnace,i started it up the other day,it came on it went through all the stages but the ignitor would not light up,its an electric ignitor. so i bought a new ignitor installed it ,but the same thing happen,the red led light is on on the control board,its not flashing,why want the ignitor work.

You go through the electrical diagram from source to ignitor to see what is not happening at one point on the way to provide electricity to the ignitor. There is a wire or switch the doesn't or won't connect.

You might get a list of guesses from novices on the internet as to where that gap is
OR
you do the electrical testing work.

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.