error: undefined refrence

[motsh]

i have an error in ficgta01 sdk 4.3.2
header file:

#ifndef THIRD_H
#define THIRD_H
#include "ui_third.h"
#include "qcbsmessage.h"
#include <QVariant>
#include <QString>
#include<QWidget>
class third:public QWidget,private Ui_third
{
 
public:
third(QWidget*parent=0,Qt::WFlags f=0);
virtual ~third();
};
#endif

#ifndef THIRD_H
#define THIRD_H
#include "ui_third.h"
#include "qcbsmessage.h"
#include <QVariant>
#include <QString>
#include<QWidget>
class third:public QWidget,private Ui_third
{

public:
third(QWidget*parent=0,Qt::WFlags f=0);
virtual ~third();
};
#endif

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sourse file :

#include "third.h"
#include<QtopiaApplication>
third::third(QWidget*parent,Qt::WFlags f):QWidget(parent,f)
{
setupUi(this);
QCBSMessage *code1=new QCBSMessage();
const uint code=code1->messageCode() ;
QVariant *variant=new QVariant(code);
QString string=variant->toString();
lineEdit->setText(string);
}
third::~third(){}

#include "third.h"
#include<QtopiaApplication>
third::third(QWidget*parent,Qt::WFlags f):QWidget(parent,f)
{
setupUi(this);
QCBSMessage *code1=new QCBSMessage();
const uint code=code1->messageCode() ;
QVariant *variant=new QVariant(code);
QString string=variant->toString();
lineEdit->setText(string);
}
third::~third(){}

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error message :

.obj/debug-shared/third.o: In function `third':
/home/user/projects/third/third.cpp:6: undefined reference to `QCBSMessage::QCBSMessage()'
/home/user/projects/third/third.cpp:7: undefined reference to `QCBSMessage::messageCode() const'
/home/user/projects/third/third.cpp:6: undefined reference to `QCBSMessage::QCBSMessage()'
/home/user/projects/third/third.cpp:7: undefined reference to `QCBSMessage::messageCode() const'
collect2: ld returned 1 exit status
make[1]: *** [third] Error 1
make[1]: Leaving directory `/home/user/projects/third'
make: *** [all] Error 2

please any one tell me what's wrong
thanks