遇到QT信号不能在派生类定义的问题 undefined referenc signals

#ifndef DEVICEPACKET_H
#define DEVICEPACKET_H

#include <QObject>
#include "protocolmetadata.h";

class DevicePacket : public QObject
{
    Q_OBJECT
public:
    explicit DevicePacket(QObject *parent = 0);
    QByteArray packetArray;

signals:
    void onemeta(ProtocolMetaData *);</strong></span>

public slots:

   virtual char *data();
   virtual int dataSize();

};

#endif // DEVICEPACKET_H

class DevicePacketZigBee : public DevicePacket
{
signals:
    void onemeta(ProtocolMetaData *);</span></strong>