What should I do if the dryer burner does not ignite during the first use?

Run the dryer on a full heat cycle (not air cycle) for at least five minutes to purge air from the gas supply line. If the burner does not ignite and no heat is felt inside the dryer, shut off the dryer for five minutes, check that all supply valve controls are in the 'ON' position and the power supply cord is plugged in, then repeat the five-minute test. (Page 6)