If your cranberry sauce isn't setting, it may be due to insufficient pectin content in the cranberries. Pectin is a natural thickening agent found in fruits, and some batches of cranberries may have lower levels. To remedy this, you can try adding commercial pectin or increase the cooking time to allow the sauce to thicken further. Additionally, ensuring the proper ratio of sugar and acid and allowing the sauce to cool adequately can contribute to achieving the desired consistency.