Thanks for reaching out! We're sorry to learn about your experience. If the tab is mostly undissolved after the cycle it is possible that a large item is blocking the dispenser cup from opening during the cycle which would prevent the tab from dispensing. Another tip is the proper water temperature. To properly dissolve dishwasher detergents, the water temperature should range from a minimum of 125 F, to the optimum temperature of 140 F. We hope this helps! For further assistance please call 1-800-228-4722 between 9:00-5:00 EST (Monday - Friday) or send an email to us at consumercare_usa@reckitt.com , including the following case number, RB0002062314 , and we would be more than happy to help. Sincerely, Your Finish Team