This Allrecipes article doesn’t really answer your question but the subsequent discussion by members may help *** http://allrecipes.com/HowTo/Slow-Cooking-is-Good-Cooking/detail.aspx ***. There is no single answer but most likely it involves cooking to long, especially if your cooker operates at a higher temp. If you have a cooking thermometer, test the temp of the meat until you get a better feel for how long it takes to properly cook. Raising the meat from touching the bottom of slow cooker may also help . . . some people use potatoes. Keep at it, and you’ll get it right.