Hello. We're sorry to hear the tab isn't dissolving properly. 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 information is helpful. As the manufacturer, if we can help more, please call 1-800-235-6052 between 9:00-5:00 EST (Monday - Friday) or send us an email via the Contact Us page on our website including the following case number RB0001095049, and we would be more than happy to help. Sincerely, Your Finish Team!