WS2811 LED strip not working

Apologies if this is in the wrong section, I've never posted before.

I recently bought a WS2811 LED strip off amazon, and used the FastLED library ( and used the example sketch Blink, but changed the line that says to use the WS2811 instead of the NeoPixel. When I run this, all the LEDs turn red and don't change. It's not the full red either, just a dim red. I returned the first one I got for this reason, but the second one did it too. I'm using an arduino uno, and the 5v port when plugged into the USB port on my computer. I've looked everywhere and either don't have the right search terms or nobody else has my problem.

Any help is greatly appreciated.

How long of a strip?

You'd need a power supply for the LED strip.