QObject::connect not connecting signal to slot

我在项目中使用C++和Qt，我的问题是QObject:：connect函数没有将信号连接到插槽。我有以下课程：

class AddCommentDialog : public QDialog
{
Q_OBJECT
public:
...some functions 
signals:
void snippetAdded();
private slots:
void on_buttonEkle_clicked();
private:
Ui::AddCommentDialog *ui;
QString snippet;
};

我主窗口的一部分：

class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void commentAddedSlot();
void variableAddedSlot();
...
private:
AddCommentDialog *addCommentDialog;
...
};

Ant最后一个对话框；

class AddDegiskenDialog : public QDialog
{
Q_OBJECT
public:
...
signals:
void variableAdded();
private slots:
void on_buttonEkle_clicked();
private:
Ui::AddDegiskenDialog *ui;
...
};

在主窗口构造函数中，我连接信号和插槽：

addCommentDialog=new AddCommentDialog();
addDegiskenDialog=new AddDegiskenDialog();
connect(addDegiskenDialog, SIGNAL(variableAdded()), this, SLOT(variableAddedSlot()));
connect(addCommentDialog, SIGNAL(snippetAdded()), this, SLOT(commentAddedSlot()));

关键是我的commentAddedSlot成功地连接到了它的信号，但commentAdddSlot失败了。有Q_OBJECT宏，没有关于没有x插槽的警告。除此之外，receivers(SIGNAL(snippetAdded()))给我1，但receivers；qmake和make进行完全编译。我错过了什么？