extjs自定义函数不能执行

var win = Ext.create('Ext.window.Window', {
                title: '登录',
                iconCls: 'locked',
                width: 400,
                height: 260,
                layout: 'fit',
                items: form,
                buttonAlign: 'center',
                resizable: false,
                closable: false,
                draggable: false,
                buttons: [{
                    text: '登录',
                    handler: this.LoginFrom,
                    scope: this
                }, {
                    text: '重置',
                    handler: function () {
                        form.getForm().reset();
                    },
                    scope: this
                }],
                LoginFrom: function () {
                    alert();
                }            });

LoginFrom为什么不能调到LoginFrom（）弹出对话框。