why doesn't this connect() function work?

[JackAlredyInUse]

I want to use lambda expression in my function,the relations between files and classes like follows:

//main.cpp
MainWIndow w;
w.show()

//MainWIndow.h
class MainWindow:public QMainWindow
{
          void initMainWindowUI();
}

//MainWindow.cpp
void MainWindow::initMainWIndowUI()
{
   QAction *colors = new QAction(ui->menuEdit);
   // this connect() work well 
   connect(colors,&QAction::triggered,this,&MainWindow::doActionColorGradient);
   ui->menuEdit->addAction(colors);
}
void MainWindow::doActionColorGradient()
{
   QSharedPointer<QDialog> colorGradientParamInputDlg(new QDialog());
   QColor firstColor;
   QToolButton *firstColorButton;
   firstColorButton = new QToolButton();
   // there is nothing happened when I clicked the firstColorButton.
   // what's wrong with my code?
   QObject::connect(firstColorButton,&QToolButton::triggered,[&]{

     firstColor = QColorDialog::getColor(QString("first color"));

   });
   
}

Appreciate if you can tell me the solutions .

[J.Hilk]

You're using &QToolButton::toggled, but a thats not enabled by default.

add the following below firstColorButton = new QToolButton()

firstColorButton ->setCheckable(true);

[JackAlredyInUse]

Thank you,But it seems not effct,and I edit

QObject::connect(firstColorButton,&QToolButton::triggered,...

to

QObject::connect(firstColorButton,&QPushButton::clicked,...

then it works.
And I'm learning the differences between triggered and clicked. XD