Good suggestions you received from others but keep in mind the AMNPS has difficulties operating at higher altitudes (yes this is something that Todd does mention for those at higher altitudes). So you need to inquire about that before purchasing. I don't have one simply because I live at over 8500 ft.
Make sure you have checked the smoker temp with the actual temp with a good calibrated thermometer. They are notorious for being off (either hotter or cooler). I have a Gen 1 MES 40 and depending on what I set the temp at, mine runs 25-50° cooler. If yours is running cooler, there is a possibility that it just wasn't hot enough to get those chips smoldering. The temp needs to be higher than 180-190° for the chips to start smoldering, until you have some hot ash in the chip pan.
I primarily use Smokehouse Pellets in mine and they work very well. I only use wood chips in flavors that I can't get the pellets in and then mix the wood chips with the pellets when smoking.