Take a look on top, i had a problem with my supplier. I ordered some TIP 120 and i had some TIP 135 (PNP). The "funny" thing is that the box was labeled TIP120 but inside, there was some TIP135, and i didn't check it... Was my fault 
I know that the TIP120 is much more than necessary in this case, but the led was here only for a test purpose. In the end i'll put 2 led lights for an amount of 40W 