I have a dependent combo box that is required. When the parent combo box value is selected, the dependent combo is cleared and the store is reloaded. How do I keep the ExtJs validation error from showing during the reload?

```
            new Ext.form.ComboBox({
                id: 'ddlMake',
                store: makeStore,
                displayField: 'Description',
                valueField: 'TypeCode',
                width: 110,
                typeAhead: true,
                mode: 'local',
                forceSelection: true,
                triggerAction: 'all',
                emptyText: 'Select a make',
                selectOnFocus: true,
                allowBlank: false,
                listeners:
                    {
                        select: function (combo, record, index) {
                            var selVal = Ext.getCmp('ddlMake').getValue();
                            var modelCombo = Ext.getCmp('ddlModel');
                            modelCombo.setValue('');
                            modelCombo.store.reload({
                                params: { categoryTypeCode: 'MODEL', subCategoryTypeCode: selVal }
                            });
                        }
                    }
            }),
            new Ext.form.ComboBox({
                id: 'ddlModel',
                store: modelStore,
                displayField: 'Description',
                valueField: 'TypeCode',
                width: 110,
                typeAhead: true,
                mode: 'local',
                forceSelection: true,
                triggerAction: 'all',
                emptyText: 'Select a model',
                selectOnFocus: true,
                allowBlank: false
            }),

```