[away3d] range error #1125

[le_unam]

hey guys ... i get a range error #1125 when i try to add all childs of
my awd-file

[Embed(source="test/test.awd", mimeType="application/octet-stream")]
private var AWDFile:Class;

var test:ObjectContainer3D = AWData.parse(new AWDFile(),
{ customPath:"./test/images/" } ) as ObjectContainer3D;
                        for (i = 0; i < 62; i++)
                        {
                                test.children[i].name = "model_" + i;
                                test.children[i].collider = true;
                                _tree.addChild(test.children[i]);
                        }

when i trace test.children.length i get 62, but when trying to add
test.children[31] or higher then i get an range error ... why? what
does this error means? the first 30 childs work fine when adding.