Qt Quick UI Forms implement signal handlers not action

when use Loader load form 

Loader

{ id: myLoader source: "Page3Form.ui.qml" }

 

the implement in Page3.qml not active,

bnSave is the delaybutton

in Page3.qml

Page3Form {Page3Form {    bnSave.onActivated: {    beDriver.bnSaveClicked() }}

 

now , I do it use like below:

 

in Page3Form.ui.qml

DelayButton

{ id: bnSave x: 454 y: 289 width: 122 height: 56 text: qsTr("Save") font.pointSize: 12 // @disable-check M222 onActivated: beDriver.bnSaveClicked() }

which beDriver is a QObject written by C++.

if Page3Form define in main.qml ,it is OK. But i want to use Loader to load many page 

to show diffent page.