DIAGNOSIS The spark electrode tip is probably dirty, misaligned, or the wire connecting it is damaged. Grease and moisture can insulate the tip, preventing a strong spark from jumping to the burner.
FIX Lift the lid and locate the small, pointed ceramic electrode near the front of the burner. You'll see a small metal tip about 1/8 inch from the burner. 1) Make sure the grill is cold and the gas is OFF. 2) Wipe the electrode and the nearby burner surface with a dry paper towel to remove any grease. 3) Use a fine-grit sandpaper or an emery board to gently scour the metal tip of the electrode and the spot on the burner it's supposed to spark to. 4) Check that the electrode wire isn't pinched or loose. Try the igniter button again.
IF THAT DIDN'T WORK The battery in the igniter module might be dead. On the Q1200, the battery compartment is on the front control panel. You'll need a small Phillips head screwdriver to open it. Replace the battery with a fresh AAA alkaline battery.
HEADS UP When using a lighter to manually light, always hold the flame at the burner ports first, *then* turn the knob to START/HI. This prevents a flash of unburned gas from building up under the lid.