LED lights wired in series will not light
I think you are using 12v LED lights. Accordingly, when you connect many LED lights in series, the 12v is going to be divided equally among the LED lights. Thus, if you have 2 LED lights, 6v for each one. If you have 3 LED lights, 4v for each one.

In your case, you should connect them in parallel to get the job done.

For more info have a look at this link.

Quouted from the previous link.


  Finally, remember that for resistors in series, the current is the
  same for each resistor, and for resistors in parallel, the voltage is
  the same for each one.