You connected your leds paralel, I think.It is a bit hard to see on the picture.
So if one led isn't visible, maybe the connection is not good(to high resistance of the welding?)You use an usb-port of you pc?If you have a problem(shortcircuit) of your setup you can blowup you motherboard.
You can buy usb adapters like on this picture.
In this picture you see the leds connected in serie, I think you should make it the same.You can leave that ptc out.
In paralel you have 3 leds using 70mA is together 210mA and with serie connection you have just 70mA running.