Hello!

I have a small problem with connecting the custom signal and the custom slot(Object::connect: No such signal)

Here is the code, what I have:

datedialog.h:

Qt Code: 
  1. #ifndef DATEDIALOG_H
  2. #define DATEDIALOG_H
  3.  
  4. #include <QDialog>
  6. class QLineEdit;
  8.  
  9. class DateDialog:public QDialog
  10. {
  11.     Q_OBJECT
  12.  
  13. public:
  14.     DateDialog(QWidget *parent = 0);
  15. signals:
  16.     void SendText(const QString &text);
  17.  
  18. private:
  19.     void Initialization();
  20.     void PlacingElements();
  21.  
  22. private slots:
  23.     void EnableOKButton(const QString &text);
  24.     void GetDateToLine();
  25.     void BeforeShowMsg();
  26.     void ShowMessageBox(const QString &text);
  27.  
  28. private:
  29. QCalendarWidget *calendar;
  30. QLineEdit *line;
  31. QPushButton *OkButton;
  32.  
  33. };
  34.  
  35. #endif // DATEDIALOG_H
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datedialog.cpp

Qt Code: 
  1. #include "datedialog.h"
  2. #include <QHBoxLayout>
  3. #include <QCalendarWidget>
  4. #include <QLineEdit>
  5. #include <QPushButton>
  6. #include <QIcon>
  7. #include <QString>
  8. #include <QMessageBox>
  9.  
  10. DateDialog::DateDialog(QWidget *parent):QDialog(parent)
  11. {
  12.     Initialization();
  13. }
  14.  
  15. void DateDialog::Initialization()
  16. {
  17.     calendar = new QCalendarWidget();
  18.     line = new QLineEdit();
  19.     line->setFocus();
  20.     OkButton = new QPushButton(QObject::tr("Press me!"));
  21.     OkButton->setDefault(true);
  22.     OkButton->setEnabled(false);
  23.     connect(this->calendar, SIGNAL(selectionChanged()),
  24.             this, SLOT(GetDateToLine()));
  25.     connect(this->line, SIGNAL(textChanged(const QString &)),
  26.             this, SLOT(EnableOKButton(const QString &)));
  27.     connect(this->OkButton, SIGNAL(clicked()),
  28.             this, SLOT(BeforeShowMsg()));
  29.    connect(this, SIGNAL(SendText(cosnt QString &)),
  30.             this, SLOT(ShowMessageBox(const QString &)));
  31.     PlacingElements();
  32. }
  33.  
  34. void DateDialog::PlacingElements()
  35. {
  36.     QHBoxLayout *leftTop = new QHBoxLayout;
  37.     leftTop->addWidget(this->line);
  38.     QHBoxLayout *leftDown = new QHBoxLayout;
  39.     leftDown->addWidget(OkButton);
  40.  
  41.     QVBoxLayout *left = new QVBoxLayout;
  42.     left->addLayout(leftTop);
  43.     left->addStretch();
  44.     left->addLayout(leftDown);
  45.  
  46.     QVBoxLayout *right = new QVBoxLayout;
  47.     right->addWidget(this->calendar);
  48.  
  49.     QHBoxLayout *main = new QHBoxLayout;
  50.     main->addLayout(left);
  51.     main->addLayout(right);
  52.  
  53.     this->setLayout(main);
  54.     this->setWindowTitle(QObject::tr("Date"));
  55.  
  56.     QString FilePath = "E:\\linux-penguin-computing.jpg";
  57.     this->setWindowIcon(QIcon(FilePath));
  58.     this->setFixedSize(sizeHint().width(), sizeHint().height());
  59. }
  60.  
  61. void DateDialog::EnableOKButton(const QString &text)
  62. {
  63.  this->OkButton->setEnabled(!text.isEmpty());
  64.  OkButton->setEnabled(true);
  65. }
  66.  
  67. void DateDialog::GetDateToLine()
  68. {
  69.  this->line->setText(calendar->selectedDate().toString("dd/MM/yyyy dddd"));
  70. }
  71.  
  72. void DateDialog::ShowMessageBox(const QString &text)
  73. {
  75.  msg.setText(text);
  76.  msg.setWindowTitle(QObject::tr("Information before closing"));
  77.  msg.setIcon(QMessageBox::Warning);
  78.  msg.exec();
  79.  this->close();
  80. }
  81.  
  82. void DateDialog::BeforeShowMsg()
  83. {
  84.     if(!line->text().isEmpty())
  85.     {
  86.      emit SendText(line->text());
  87.     }
  88. }
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main.cpp:

Qt Code: 
  1. #include <QtGui/QApplication>
  2. #include "datedialog.h"
  3.  
  4. int main(int argc, char *argv[])
  5. {
  6.     QApplication app(argc, argv);
  7.  
  8.     DateDialog date;
  9.     date.exec();
  10.  
  11.     return app.exec();
  12. }
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The first question that I have is: why?
And the second one is: How it can be rectified?

Thank you beforehand for answers.