Sandisk Cruzer not recognized by Windows 7

Try this simple tip. I bought a batch of these and only two worked. I had a small (24") male/female extension lead which I used and they all work fine. My guess is the contacts aren’t connecting properly. My first thoughts were aroused because they were difficult/tight to insert into some pc slots. I would suggest a good quality extension lead in case a cheap one creates the same problem. I hope you find this cheap, cheerful and above all else, simple.