Ext JS Issue, Date field showing NaN/NaN/NaN

var proxy = new Ext.data.HttpProxy({
  	  api: {
    	    read : 'view',
      	  create : 'create',
        	update: 'update',
	        destroy: 'destroy'
  	  }
	});
 
	var reader = new Ext.data.JsonReader({
  	  totalProperty: 'total',
    	successProperty: 'success',
	    idProperty: 'id',
	    root: 'data'
	}, [
  	  {name: 'id'},
	    {name: 'game_date', xtype: 'datecolumn', format: 'm/d/Y', allowBlank: false},
	    {name: 'time', allowBlank: false},
	    {name: 'home_team', allowBlank: false},
	    {name: 'visiting_team', allowBlank: false},
	    {name: 'playing_field', allowBlank: false},			
	]);
 
	var writer = new Ext.data.JsonWriter({
	    encode: true,
	    writeAllFields: false
	});
			
	var store = new Ext.data.Store({
  	  id: 'user',
    	proxy: proxy,
	    reader: reader,
  	  writer: writer,
    	autoSave: false,
	    listeners: {
  	      write : function(store, action, result, res, rs) {
    	        Ext.Msg.alert("Notice", res.message);
      	  },
        	exception : function(proxy, type, action, options, res, arg) {
          	  if (type === 'remote') {
            	    Ext.Msg.show({
              	      title: 'REMOTE EXCEPTION',
                	    msg: res.message,
                  	  icon: Ext.MessageBox.ERROR,
                    	buttons: Ext.Msg.OK
	                });
  	          }
    	    }
    	}
	});
 
	store.load();
	var grid;
	    grid = new Ext.grid.EditorGridPanel({
        store: store,
        columns: [
            { id: 'game_date', header: "Date", width: 160, sortable: true, dataIndex: 'game_date', renderer: Ext.util.Format.dateRenderer('m/d/Y'), editor: new Ext.form.DateField({ format: 'm/d/Y', allowBlank: false })},
            {header: "Time", width: 75, sortable: true, dataIndex: 'time', editor: new Ext.form.TimeField({ allowBlank: false })},
            {header: "Home Team", width: 75, sortable: true, dataIndex: 'home_team', editor: new Ext.form.TextField({ allowBlank: false })},
            {header: "Visiting Team", width: 75, sortable: true, dataIndex: 'visiting_team', editor: new Ext.form.TextField({ allowBlank: false })},
            {header: "Playing Field", width: 85, sortable: true, dataIndex: 'playing_field', editor: new Ext.form.TextField({ allowBlank: false })}
        ],
	tbar: [
	{
            text: 'Add',
            iconCls: 'silk-add',
            handler: function(btn, ev) 
	    {
                var u = new store.recordType({
                    game_date : '',
                    time: '',
                    home_team : '',
		    visiting_team : '',
		    playing_field : ''
                });
								
                grid.stopEditing();
                store.insert(0, u);
                grid.startEditing(0, 1);
    				},
            scope: this
        }, '-', {
            text: 'Delete',
            iconCls: 'silk-delete',
            handler: function(btn, ev) 
	    {
                var index = grid.getSelectionModel().getSelectedCell();
                if (!index)
                    return false;
                var rec = store.getAt(index[0]);
                store.remove(rec);
            },
            scope: this
        }, '-'],
	buttons: [{
            text: 'Save',
            iconCls: 'icon-save',
            handler: function(btn, ev) 
	    {
               store.save();
            },
            scope: grid
        }],
	clicksToEdit: 2,
        stripeRows: true,
        autoExpandColumn: 'game_date',
        height:350,
        width:600,
        title:"Game Schedule"
    });
    grid.render('grid-example');

                                  

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