attempt to compare two nil values. jbeam error beamng

hi, i am working on a mod and redid the jbeam(with BNE editer) and it gave me attempt to compare two nil values error my syntax looks fine what am i doing wrong???

jbeam:
{
"cube":{
"information":{
"name":"cube",
"authors":"myrccar",
"type":"prop",
},
"slotType":"main",
"refNodes":[
["ref:", "back:", "left:", "up:", "leftCorner:", "rightCorner:"],
["0", "1", "2", "3", "4", "5"],
],
"variables": [
["name", "type", "unit", "category", "default", "min", "max", "title", "description"],
["$weight", "range", "kg", "", 40, 0, 10000, "weight", "Adjust the weight", {"stepDis":1}],
],
"nodes":[
["id", "posX", "posY", "posZ"],
{"group":"cube"},
{"nodeWeight":"$weight"},
["0", 1.00000, 1.00000, -1.00000],
["1", 1.00000, -1.00000, -1.00000],
["2", 1.00000, 1.00000, 1.00000],
["3", 1.00000, -1.00000, 1.00000],
["4", -1.00000, 1.00000, -1.00000],
["5", -1.00000, -1.00000, -1.00000],
["6", -1.00000, 1.00000, 1.00000],
["7", -1.00000, -1.00000, 1.00000],
["8", 0.00000, 0.00000, 1.00000],
["a2", 1.00000, 0.00000, 0.00000],
["a3", -1.00000, 0.00000, 0.00000],
["a4", 0.00000, -1.00000, 0.00000],
["a5", 0.00000, 1.00000, 0.00000],
["a6", 0.00000, 0.00000, -1.00000],
{"group":""},
],
"beams":[

["0", "4"],
["4", "6"],
["6", "2"],
["3", "2"],
["2", "6"],
["6", "7"],
["7", "6"],
["6", "4"],
["4", "5"],
["5", "1"],
["1", "3"],
["3", "7"],
["1", "0"],
["0", "2"],
["2", "3"],
["5", "4"],
["4", "0"],
["0", "1"],
["7", "5"],
["6", "8"],
["2", "8"],
["8", "3"],
["7", "8"],
["3", "a2"],
["a2", "2"],
["a2", "0"],
["a2", "1"],
["2", "a5"],
["6", "a5"],
["a5", "4"],
["a5", "0"],
["6", "a3"],
["7", "a3"],
["a3", "5"],
["a3", "4"],
["7", "a4"],
["3", "a4"],
["a4", "1"],
["a4", "5"],
["4", "a6"],
["5", "a6"],
["0", "a6"],
["1", "a6"],

//BNEbeams


],
"triangles":[
["7", "8", "6"],
["3", "8", "7"],
["2", "8", "3"],
["6", "8", "2"],
["4", "a5", "0"],
["6", "a5", "4"],
["2", "a5", "6"],
["0", "a5", "2"],
["5", "a3", "4"],
["7", "a3", "5"],
["6", "a3", "7"],
["4", "a3", "6"],
["1", "a4", "5"],
["3", "a4", "1"],
["7", "a4", "3"],
["5", "a4", "7"],
["0", "a2", "1"],
["2", "a2", "0"],
["3", "a2", "2"],
["1", "a2", "3"],
["4", "a6", "5"],
["0", "a6", "4"],
["1", "a6", "0"],
["5", "a6", "1"],

//BNEtriangles


],
"flexbodies" :[
["mesh","[group]:","nonFlexMaterials"],
["cube",["cube"]],
],

"cameraExternal":{
"distance":4.5,
"distanceMin":1.5,
"offset":{"x":0.0, "y":0.2, "z":0.45},
"fov":65,
},
}
}

 

thanks,
what's missing?
it worked > redid jbeam(nodes and beams and tris) > it did not work?