The problem is probably the cheese you are using. Most people use pre-shredded mozzarella cheese to make pizza at home. Even though mozzarella doesn’t have much flavor, its texture and elasticity make it the ideal pizza cheese. The problem with mozzarella is that it is that it has a lot of water in it compared to cheddar, Swiss, or American. Because mozzarella is soft and has a lot of moisture in it, pre-shredded mozzarella sticks together very easily. Because of that, nearly all the pre-shredded mozzarella cheese sold in the United States is coated with cellulose, or sawdust. (Yes, you read that right. I did say sawdust.) The next time you are planning to buy a bag of ‘pizza cheese’, read the ingredients on the bag. Most brands will list the cellulose. A few brands use potato or corn starch instead of sawdust. All these all powdery coatings keep the cheese from sticking together into one big glob, but they also prevent the cheese from melting the way you want it to. The solution is simple. When making pizza at home, don’t buy pre-shredded mozzarella cheese. Buy a ball of mozzarella and shred it yourself when you are making your pizza. Its a little extra work, but the texture and appearance of your finished pizza will be entirely different from what you get when use supermarket ‘pizza cheese.’ Also, try to get mozzarella that is made from fresh milk. A lot of mozzarella cheese is made from condensed skim milk or nonfat dry milk, both of which are cheaper than fresh milk but they make inferior cheese. A good mozzarella cheese ball costs about the same price per pound as pre-shredded mozzarella cheese covered with sawdust, so why not use the good stuff?