Please check the following:
1. Dishes have not been placed correctly; please refer to the "Basket" instructions in the manual.
2. The washing programme intensity is insufficient; please select a stronger programme.
3. Insufficient dishwasher detergent has been added; please use more detergent.
4. Dish placement is affecting the spray arm rotation; please rearrange the dishes to allow free rotation of the spray arm.
5. The filter has not been cleaned regularly or has not been properly fitted into the base; please clean the filter regularly or fit it correctly.