Error: Cannot find referenced group. Possible reason: items added before groups? Groups need to be added before items, as items refer to groups.

[GowrishankarGeek]

var dataGroups = new VisDataSet();
dataGroups.add({id: "in", content: 'Group 1'});
dataGroups.add({id: "out", content: 'Group 2'});
dataGroups.add({id: "txrx", content: 'Group 3'});

    var cpuGraph = new VisDataSet();
    var memoryGraph = new VisDataSet();
    var netGraph = new VisDataSet();
    var diskGraph = new VisDataSet();

    cpuGraph = data.result.cpu
    memoryGraph = data.result.mem
    netGraph = data.result.nw
    diskGraph = data.result.disk

i couldn't find what is the issue here