I have followed the directions, you tubed how etc. i start my grill, set the temp to L after the plum of smoke etc attempt to set the temp to 225 to smoke ribs. Temp climbs to 225 but does not stop. Last time I let it get to 250, turned the temp down to 215 and the grill temp fell to about 230. New grill, new pellets etc. what am I doing wrong? Very frustrated.