APA102 + Pico (problem on write data)

I have some trouble writing data to APA102 LED strip.
In my example I just do the same as the documentation said.

1. 4 bytes of 0x00 as a start frame.
   
2. For each LED, a brightness byte (0xE0 + value), a blue value byte, a green value byte, and a red value byte.
   
3. (N/2)/8 bytes of 0xFF as an end frame, where N is the number of LEDs.
   
   

result is following source:

SPI2.setup({mosi:B15, sck:B13, baud:4000000});

var NumLEDs = 150;
var leds = new Uint8Array(NumLEDs*4);

function draw() {
  var millis = getTime();

  var r = Math.random()*255;
  var g = Math.random()*255;
  var b = Math.random()*255;
  for (var pixel = 0; pixel < leds.length; pixel+=4)
  {
    leds[pixel+0] = 0xE0 | 5;
    leds[pixel+1] = b;
    leds[pixel+2] = g;
    leds[pixel+3] = r;
  }
  write_leds(leds, NumLEDs);
}

function write_leds(leds, numLeds) {
  var halfLed = numLed/16 + 1; // compute end frame length
  var maxIndex = numLed * 4; // maximum leds row index;
  var index; 
  SPI2.write(0x00);
  SPI2.write(0x00);
  SPI2.write(0x00);
  SPI2.write(0x00);
  
  // LED Frame
  for (index = 0; index < maxIndex; index+=4) {
    SPI2.write(leds[index+0]);  // global brigthness 
    SPI2.write(leds[index+1]);  // B
    SPI2.write(leds[index+2]);  // G
    SPI2.write(leds[index+3]);  // R
  } // for all leds

  // End Frame
  for (index = 0; index < halfLed; index++) {
    SPI2.write(0xFF);
  } // for end frame
} // write_leds()

function onInit() {
  setInterval(draw, 50);
}

onInit();

But it seems that the data I send is not the data I see.
Also if I change the pixel data to show only red pixels; there is always a kind of random colors to see :/

Hope someone can help me here to fix the problem.