My first thought was that you put both blades in the cutter. There are 2 in a package and sometimes they are stuck together. If that isn't the case, then do take them back... I have bought several packages and have found just one pack that was 'dull', still cut, but not clean. Just changed it out. More gas to make a special trip back to exchange than to open a new package. That one cut paper just fine. Good luck and don't give up on them....