Sometimes a four stroke doesn't get enough prime by pulling the prop through. Put your finger over the exhaust outlet with the glow battery connected. Spin the engine with the starter until the engine fires. Watch out for the prop!! I've managed to get my forearm in the prop a time or two when the plane moved while starting. I highly suggest using a helper to either plug the exhaust or spin the starter. After the first start it will usually start by just applying the starter. Good luck.

Paul