Error while using fieldset

[Supriya Kale]

Hi,
I am using 'fieldset' so as to group few of the controls. But as soon as I try to specify 'collapsed' as true, I get js error saying 'targetContext' is undefined. Is there some other way around so as to set the fieldset collapsed initially?

Please find my code below:

Ext.define('APP.view.SampleForm',{

    extend: 'Ext.form.Panel',
    alias:'widget.sampleform',
    layout:{
        type:'vbox'
    
    },
    padding:'5 5 5 5',
    renderTo: Ext.getBody(),
    
    items:[{
        xtype:'textfield',
        fieldLabel:'Name'
    },{
        // Fieldset in Column 2 - collapsible via checkbox, collapsed by default, contains a panel
        xtype:'fieldset',
        title: 'Show Panel', // title or checkboxToggle creates fieldset header
        columnWidth: 0.5,
        checkboxToggle: true,
        collapsed: true, // fieldset initially collapsed
        layout:'anchor',
        items :[{
            xtype: 'panel',
            anchor: '100%',
            title: 'Panel inside a fieldset',
            frame: true,
            height: 52
        }]
    }],
    initComponent: function(){
        this.callParent(arguments);
    
    }


});

[friend]

Try adding collapsible: true, directly above collapsed: true. collapsible defaults to a value of false, if not configured manually..