My APA102 LED isn't working properly. Only the first LED (nearest Arduino Uno connected USB) lights up and cycles through but it isn't controllable from the command line. Sometimes the 2nd, 3rd & 4th LEDs light up too, less often more random LED light will light up along the strip but only faintly and don't cycle. Only the LED nearest the Arduino lights up properly and cycles. I'm confident in the power adapter, less so the connections to it. When I first plug in the strip all of the LEDs light up for a fraction of a second. If anyone could point me in the right direction I'd really appreciate is, is the strip a dud or is it a power/ grounding issue?