Okey you were right, I thinnk the JSON vas in 2D and construct 2 requires it in 3D.
If anyone has the same problem, this was my first JSON:
{"c2array":true,"size":[4,4,1],"data":[[0,50,100,150],[0,500,1000,2000],[0,1000,2000,3000],[0,1500,5000,10000]]}
And this is the correct format:
{"c2array":true,"size":[4,4,1],"data":[[[0,50,100,150]],[[0,500,1000,2000]],[[0,1000,2000,3000]],[[0,1500,5000,10000]]]}
You can close it as it is not a bug, thanks everyone!