My USBasp programmer came with a 10-pin ICSP cable. The Arduino has a 6-pin ICSP header. Did you get a 10-Pin to 6-Pin adapter? Are you sure you have it connected the right way around? The 6-pin header on the Arduino UNO is not keyed so you can accidentally plug the cable in backwards. Does the power LED light up when you plug in the programmer? Mine does.