Ambiligt TV help plz??

Hi guys,

I struggling now several weeks to make ambilight work with my TV.

I using WS2812B led
Andruino mega
External power supply 5V 20A
258 leds
4 rows one on each side
Ambibox software
Sketch code is attached.

Now to the problem.

When running RGB test with one colors everything works great but when a color circles around the TV the white color is emitted right on bottom and right side but its wrong on the left and top side. The other colors what I can see is good with no problem.

Whats the problem?

Problem number 2 I have 258 leds when running the code with 258 I canĀ“t make Ambibox to work. everything over 254 not working?

my sketch.ino (2.96 KB)