Can I power Neopixel ring with iPad adapter?

[Kokodoko]

I am testing my new Neopixel ring (12 leds). I am connecting it to my Arduino board, powered by 5V and max 0.5 mA.
I have put the brightness pretty low so the 12 Leds can't draw too much amps from the Arduino.

The Ring + and - are connected to the Arduino's 5V out and GND and there is a 1000 mf Capacitor also connected to the + and -, exactly like in all the instructions found here on Adafruit. There is a 330 Ohm resistor on the side of the neopixel ring's data input.

This works perfectly fine so the ring seems OK!

Now when I connect the ring to an external power source using an iPad adapter (5V output, 2mA max) then it ALMOST works, except that the first LED randomly blinks green together with some of the other pixels. (setting pixel 4 to blue, also sets pixel 1 to green)

Connecting another weaker power source (a mobile phone charger with 5V output and 0.5mA) lights up ALL the LED's very brightly so this is obviously a wrong adapter.

My question, what is going wrong here, how do I know what power adapter I can use? Isn't it enough to just check the Voltage and Amp output of an adapter?

[adafruit_support_bill]

Any regulated 5v supply should work. Connect the supply ground directly to the ring, but also run a wire from the Arduino GND to the ring GND. To avoid pixel damage, the GND connections should be the first connections you make: http://learn.adafruit.com/adafruit-neop ... -practices

[Kokodoko]

Thanks! That was it.. can't believe I missed that after reading the tutorial a 1000 times!