QXML* and QSax not found (A2Q3)

Language: C++ (QT)
In file included from main.cpp:1:
myhandler.h:4:30: QXmlDefaultHandler: No such file or directory
In file included from main.cpp:1:
myhandler.h:6: error: expected class-name before ';{'; token
myhandler.h:12: error: expected `,'; or `...'; before ';&'; token
myhandler.h:12: error: ISO C++ forbids declaration of `QXmlAttributes'; with no t
ype
myhandler.h:18: error: field `indent'; has incomplete type
main.cpp:3:27: QXmlInputSource: No such file or directory
main.cpp:4:28: QXmlSimpleReader: No such file or directory
main.cpp: In function `int main(int, char**)';:
main.cpp:14: error: `QXmlInputSource'; undeclared (first use this function)

Language: C++ (QT)
#ifndef MYHANDLER_H
#define MYHANDLER_H
//start
#include <QXmlDefaultHandler>
class QString;
class MyHandler : public QXmlDefaultHandler {
  public:
    bool startDocument();
    bool startElement( const QString & namespaceURI,
                       const QString & localName,
                       const QString & qName,
                       const QXmlAttributes & atts);
    bool characters(const QString& text);
    bool endElement( const QString & namespaceURI,
                     const QString & localName,
                     const QString & qName );
  private:
    QString indent;
};
//end
 
#endif        //  #ifndef MYHANDLER_H