You're likely starting with ingredients that are too cold or have overfilled the stoneware.
First, make sure you're using the right settings. The settings are Low, High, and Warm. For initial heating, always start on High. It can take 30 minutes or more to get up to a simmer.
Here's what to check:
- Fill level: The stoneware should be at least half full, but never more than 1 inch from the top rim. Too little food heats slowly.
- Starting temp: Using refrigerated or frozen ingredients dramatically increases heat-up time. For faster results, use room-temperature liquids or pre-heat them slightly.
- Lid seal: Ensure the lid is on securely. A poor seal lets heat escape, slowing everything down.
If that didn't work, test the cooker. Plug it into a different outlet. Fill it 2/3 with water, set it to High, and put the lid on. Check the water temperature after 2 hours with a food thermometer. It should be at least 185°F. If not, the heating element may be faulty.