Script to read layers not working as expected (?)

groups sample

var idoc = app.activeDocument;
var layers = idoc.layers;
var main_layer = layers[0];
var main_groups = main_layer.groupItems;

alert(main_groups.length);

Hi,

Children 1 and Children 2 are not layers. You can check by blue color left to the layer name. When we create a layer, by default each layer have different color inless and untill you make it as same color.

Thanks

Are you sure those are sub-layers and not groups?