Help please. Have 3 butts, 9 lb. average size, on my Large. They have been on for almost 90 minutes and I can't get dome temp above 200. Bottom vent wide open, Daisy opened max. Have a nice breeze and I have plenty of smoke and fire appears to be cranking. I tested dome themometer with boling water and it is spot on. What do I do? Was planning an 18 hour cook with 250 dome temp but can't get there? Am I just being too impatient??? Any thoughts appreciated.