Yabo,
When you say you don't have smoke, are you referring to visible smoke exiting the vent on top of the unit? If so, understand that there sbould still be ample smoke inside the chamber. Much like charcoal that burns hot and then smolders at an ashy gray, your wood is still releasing smoke but the color is much harder to see. Do you smell smoke when you go near your smoker? Then you've got smoke. Do you see smoke when you open the door? Same thing. Thin blue smoke, rather than cloudy white or gray, is optimal for smoking meat so don't stress if you can't see it ... stick with 3-4oz. for ribs or 5-6oz. for brisket or butt and you should be good to go.
With regard to flareups, the linked thread Divot posted does discuss what some Smokin-It owners have expressed and, more often than not, there's a simple explanation.