Light the pellet tube with a propane/butane torch, let it get going good for a few minutes, blow the flame out if there is still one, and proceed with your cook as usual. Your cook chamber doesn't have sufficient heat to light it on its own, else you would burn everything you put on it. If you are trying to use a chip box like for a gas grill, that won't light on its own either at the temps in the chamber. Pellet tubes are the best way to go with pellet grills ...... either with straight pellets, pellets mixed with chips, or dust made from pellets.