I have a round Magma BBQ on the boat. I've tried to light it many times but it always goes out after about 3 or 4 minutes. The gas bottle is full. There is a sliding thing over a hole at the end of the gas connection of the Magma, but it doesn't make any difference how much air mixes with the gas. Can someone give me step by step instructions on how to light it please. I can't find anything on the net.