Thank you for posting your review, we are sorry to hear that you are not satisfied with the performance of the DAP® SILICONE MAX ™ Premium Kitchen and Bath 100% Silicone Sealant. There are a number of factors and conditions that can result in issues with biological contamination (mold/mildew) such as application of fresh sealant to areas where contamination was already present, areas with standing water etc. DAP offers a Lifetime Guarantee on this product: DAP warrants this product for sealant purposes during the lifetime of your home when applied within one year of purchase and as directed. If product fails to perform when used as directed, return container and sales receipt to DAP Products Inc., TCS, 2400 Boston St., Baltimore, MD 21224 for replacement product or sales price refund. DAP will not be liable for incidental or consequential damages.