formBind and datefields - formBind: true not working

[qt4x11]

I have a form with two inputs which are datefields. I have formBind set on my form buttons so that the 'Submit' button is greyed out until the form is valid. It looks like formBind: true is not working. The 'Submit' button is never greyed out, even if I manually delete the selected dates for both fields. My form looks like

Ext.define('Ext.reports.CompanyCustomerSummaryForm', {
	extend : 'Ext.form.Panel',
	alias : 'widget.reports-companyCustomerSummaryForm',
	buttonAlign : 'center',
	title : 'Search',
	collapsible : true,


	layout : {
		type : 'vbox',
		align : 'center'
	},
	frame : true,


	// The fields
	defaultType : 'textfield',
	items : [{
				xtype : 'datefield',
				fieldLabel : 'From',
				labelAlign : 'left',
				name : 'from_date',
				itemId : 'from_date',
				maxValue : new Date(), // limited to the current date
				flex : 1
			}, {
				xtype : 'datefield',
				fieldLabel : 'To',
				labelAlign : 'left',
				name : 'to_date',
				itemId : 'to_date',
				value : new Date(), // defaults to today
				flex : 1
			}],


	// Reset and Submit buttons
	buttons : [{
				text : 'Reset',
				handler : function() {
					this.up('form').getForm().reset();
				}
			}, {
				text : 'Submit',
				formBind : true, // only enabled once the form is
				// valid
				disabled : true,
				handler : function() {
					var form = this.up('form').getForm();
					if (form.isValid()) {
						var grid = Ext.ComponentQuery.query('#ccsGrid')[0];
						var from_date = Ext.ComponentQuery.query('#from_date')[0];
						var to_date = Ext.ComponentQuery.query('#to_date')[0];
						// converts Date object value to a string of
						// 'yyyy-mm-dd'.
						var startDateString = Ext.util.Format.date(from_date
										.getValue(), 'Y-m-d');
						var endDateString = Ext.util.Format.date(to_date
										.getValue(), 'Y-m-d');
						grid.getStore().load({
									params : {
										startDate : startDateString,
										endDate : endDateString
									}
								});


						/*form.submit({
									waitMsg : 'Searching',
									success : function(form, action) {
										Ext.Msg.alert('Success',
												action.result.msg);
									},
									failure : function(form, action) {
										Ext.Msg.alert('Failed',
												action.result.msg);
									}
								});*/
					}
				}
			}]
});

--I'm not sure why formBind is not working, maybe I'm misunderstanding how formBind: true works with datefields. Any suggestions are appreciated. Thank yoU!.

[mitchellsimoens]

You should put allowBlank to false on a field to set the formBind work. Right now you don't have any validations to disable the submit button. I put allowBlank : false on the From datefield and it worked for me.

[qt4x11]

Thank you! worked like a charm.