I have the Masterbuilt 30" electric smoker. Like Reefsquatter wrote, getting smoke can be tricky.
If you have the older Masterbuilt the smoking capabilities are weak. They offer a free retrofit with a chip tray that is twice as big as the original. The first picture shows the newer tray on top and the older one on the bottom.
I also just got an awesome smoke generator called the A-Maze-N Smoker. It will produce smoke for about 10 hours. It uses pellets or sawdust. I got about 3 hours of smoke from the portion that is burned in the picture. And you can use it to cold smoke Salmon or cheese.
![](http://i941.photobucket.com/albums/ad251/the1jonc/2013-02-24_21-00-29_787_zps133cf5c7.jpg)