there is a "temp" button, an "on/off" button, and an "up time" and "down time" button on this cooker, but i cannot get the cooker to stay on. after a while the cooker seems to turn off and the food inside doesn't seem to cook. the temp button allows me to set it to "low" "high" or "auto" but none of the settings seem to keep the cooker on. any help would be appreciated.