QObject::connect：无法连接（特定信号）到（空）

Question

我试图在 QDockWidget 中添加多个选项卡，该选项卡由 sView 类继承。为此，我编写了定制的信号和槽。
但我收到以下错误。

QObject::connect: Cannot connect myView::EnableWindow() to (null)::ShowWindow()
  

mainWindow.h

class mainWindow : public mainWindow
Q_OBJECT       
public slots:
void ShowWindow(); 

mainWindow.cpp

void mainWindow::ShowWindow()
{
    if (!_sView->isHidden()) 
    {
        sView* newObject = new sView();
        addDockWidget(Qt::BottomDockWidgetArea,newObject );
        tabifyDockWidget(sView,newObject);
    }
}         

sView.h

class sView : public QDockWidget
{
    Q_OBJECT      
signals:
    void EnableWindow();
}  
  

sView.cpp

sView::sView() 
{     
    connect(this, SIGNAL(EnableWindow()), GetInstance()->GetMainWindowObj(),SLOT(ShowWindow()));
}

如何解决这个问题？