ViewModel stores help

Hi,

I'm new to ExtJS 5. I can't figure out how to get the stores in my ViewModel to work properly. I want the stores to get data from a json file. The ajax call is successful because I can see the http request to the users.json file. It must not be loading the data correctly into the stores. If I hard code the stores then it works. BTW, I am binding the data to a grid. I'm sure it's something simple. Thanks..

Code:

//MainModel.js file
Ext.define('sD.view.main.MainModel', {
    extend: 'Ext.app.ViewModel',


    alias: 'viewmodel.main',


/***** defining stores like this works
    stores: {
        data: {
            fields: ['id', 'name', 'email'],
            data: [
                {id: 101, name: 'Ed',    email: 'ed@sencha.com'},
                {id: 102, name: 'Tommy', email: 'tommy@sencha.com'}
            ]
        }
    }
*/
// defining like this doesn't work
    stores: Ext.create('Ext.data.Store', {
        autoLoad: true,
        fields: ['id', 'name', 'email'],
        proxy: {
            type: 'ajax',
            url: '/app/view/main/users.json',
            reader: {
                type: 'json',
                rootProperty: 'data',
                successProperty: 'success'
            }
        }
    })
});

//users.json file
{
    success: true,
    data: [
        {id: 101, name: 'Ed',    email: 'ed@sencha.com'},
        {id: 102, name: 'Tommy', email: 'tommy@sencha.com'}
    ]
}