FastLED Fire2012 X2 effect (not working)

#include <FastLED.h>

#define CLOCK_PIN     D2
#define DATA_PIN     D3
#define COLOR_ORDER BGR
#define CHIPSET     APA102
#define NUM_LEDS_X2    60
#define NUM_LEDS       30

#define BRIGHTNESS  50
#define FRAMES_PER_SECOND 100

bool gReverseDirection = false;

CRGB leds[NUM_LEDS];

void setup() {
  Serial.begin(115200);
  delay(3000); // sanity delay
  FastLED.addLeds<CHIPSET, DATA_PIN,CLOCK_PIN, COLOR_ORDER>(leds, NUM_LEDS_X2).setCorrection( TypicalLEDStrip );
  FastLED.setBrightness( BRIGHTNESS );
}

void loop()
{
  // Add entropy to random number generator; we use a lot of it.
  // random16_add_entropy( random());
  Fire2012(); // run first half of simulation frame
  FastLED.show(); // display this frame
  FastLED.delay(1000 / FRAMES_PER_SECOND);
}

#define COOLING  55

#define SPARKING 120

void Fire2012()
{
// Array of temperature readings at each simulation cell
  static byte heat[NUM_LEDS];

  // Step 1.  Cool down every cell a little
    for( int i = 0; i < NUM_LEDS; i++) {
      heat[i] = qsub8( heat[i],  random8(0, ((COOLING * 10) / NUM_LEDS) + 2));
    }

    // Step 2.  Heat from each cell drifts 'up' and diffuses a little
    for( int k= NUM_LEDS - 1; k >= 2; k--) {
      heat[k] = (heat[k - 1] + heat[k - 2] + heat[k - 2] ) / 3;
    }

    // Step 3.  Randomly ignite new 'sparks' of heat near the bottom
    if( random8() < SPARKING ) {
      int y = random8(7);
      heat[y] = qadd8( heat[y], random8(160,255) );
    }

    // Step 4.  Map from heat cells to LED colors
    for( int j = 0; j < NUM_LEDS; j++) {
      CRGB color = HeatColor( heat[j]);
      int pixelnumber=j;
         Serial.print("Pix ");
         Serial.println(pixelnumber);
        leds[pixelnumber] = color;
        pixelnumber = (NUM_LEDS_X2-1) - j;
         Serial.print("Pix ");
         Serial.println(pixelnumber);
        leds[pixelnumber] = color;
    }
}