Problem in compilation with custom metatype

I have a custom metatype declared as shown below -

Code:

---

class thumbnaildata : public QObject
{
    Q_OBJECT
 
public:
    thumbnaildata();    //default ctor
    thumbnaildata( QPixmap aPixmap,QString aPmapFilePath ); //ctor with parameters
    thumbnaildata( const thumbnaildata& other );            //mandatory copy ctor
 
    ~thumbnaildata();
 
    void setPixmap( QPixmap aPixmap );
    void setFilePath( QString aPmapFilePath );
 
    QPixmap getPmap();
    QString getPmapFilePath();
 
private:
    QPixmap mMypixmap;
    QString mPixmapFilePath;
 
};
 
Q_DECLARE_METATYPE( thumbnaildata )

---

When I compile this definition & use it in a model class ( compatible with QVariant ), I am getting the following error -

" Error: #145: member "thumbnaildata::staticMetaObject" may not be initialized
const QMetaObject thumbnaildata::staticMetaObject = { "

What is the issue & has anyone faced this issue before ?

Please show us the line which cause that error.