Data von Serialport auslesen

hallo,
von http://www.codeproject.com/KB/system/serial.aspx möchste ich ein Programm schreiben, um AT Befehle nach Serial Port zu schicken und die Antwort zu bekommen.
Beim Senden funktioniert es einwandfrei. Aber ich bekomme Antwort nicht wie ich erwartet ( statt OK bekomme ich mein Befehl).
Wo liegt das Problem? Ich danke euch im Vorraus.

Hier ist die Code von Codeproject:
CSerial::CSerial()
{

memset( &m_OverlappedRead, 0, sizeof( OVERLAPPED ) );
memset( &m_OverlappedWrite, 0, sizeof( OVERLAPPED ) );
m_hIDComDev = NULL;
m_bOpened = FALSE;

}

CSerial::~CSerial()
{

Close();

}

BOOL CSerial::Open( int nPort, int nBaud )
{

if( m_bOpened ) return( TRUE );

char szPort[15];
char szComParams[50];
DCB dcb;

wsprintf( szPort, "COM%d", nPort );
m_hIDComDev = CreateFile( szPort,
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED,
NULL );
if( m_hIDComDev == NULL ) return( FALSE );

memset( &m_OverlappedRead, 0, sizeof( OVERLAPPED ) );
memset( &m_OverlappedWrite, 0, sizeof( OVERLAPPED ) );

COMMTIMEOUTS CommTimeOuts;
CommTimeOuts.ReadIntervalTimeout = 0xFFFFFFFF;
CommTimeOuts.ReadTotalTimeoutMultiplier = 0;
CommTimeOuts.ReadTotalTimeoutConstant = 0;
CommTimeOuts.WriteTotalTimeoutMultiplier = 0;
CommTimeOuts.WriteTotalTimeoutConstant = 5000;
SetCommTimeouts( m_hIDComDev, &CommTimeOuts );

wsprintf( szComParams, "COM%d:%d,n,8,1", nPort, nBaud );

m_OverlappedRead.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
m_OverlappedWrite.hEvent = CreateEvent( NULL, TRUE, FALSE,NULL);

dcb.DCBlength = sizeof( DCB );
GetCommState( m_hIDComDev, &dcb );
dcb.BaudRate = nBaud;
dcb.ByteSize = 8;
unsigned char ucSet;
ucSet = (unsigned char) ( ( FC_RTSCTS & FC_DTRDSR ) != 0 );
ucSet = (unsigned char) ( ( FC_RTSCTS & FC_RTSCTS ) != 0 );
ucSet = (unsigned char) ( ( FC_RTSCTS & FC_XONXOFF ) != 0 );
if( !SetCommState( m_hIDComDev, &dcb )
!SetupComm( m_hIDComDev, 10000, 10000 )
m_OverlappedRead.hEvent == NULL
m_OverlappedWrite.hEvent == NULL ){
DWORD dwError = GetLastError();
if( m_OverlappedRead.hEvent != NULL ) CloseHandle( m_OverlappedRead.hEvent );
if( m_OverlappedWrite.hEvent != NULL ) CloseHandle( m_OverlappedWrite.hEvent );
CloseHandle( m_hIDComDev );
return( FALSE );
}

m_bOpened = TRUE;

return( m_bOpened );

}

BOOL CSerial::Close( void )
{

if( !m_bOpened m_hIDComDev == NULL ) return( TRUE );

if( m_OverlappedRead.hEvent != NULL ) CloseHandle( m_OverlappedRead.hEvent );
if( m_OverlappedWrite.hEvent != NULL ) CloseHandle( m_OverlappedWrite.hEvent );
CloseHandle( m_hIDComDev );
m_bOpened = FALSE;
m_hIDComDev = NULL;

return( TRUE );

}

BOOL CSerial::WriteCommByte( unsigned char ucByte )
{
BOOL bWriteStat;
DWORD dwBytesWritten;

bWriteStat = WriteFile( m_hIDComDev, (LPSTR) &ucByte, 1, &dwBytesWritten, &m_OverlappedWrite );
if( !bWriteStat && ( GetLastError() == ERROR_IO_PENDING ) ){
if( WaitForSingleObject( m_OverlappedWrite.hEvent, 1000 ) ) dwBytesWritten = 0;
else{
GetOverlappedResult( m_hIDComDev, &m_OverlappedWrite, &dwBytesWritten, FALSE );
m_OverlappedWrite.Offset += dwBytesWritten;
}
}

return( TRUE );

}

int CSerial::SendData( const char *buffer, int size )
{

if( !m_bOpened m_hIDComDev == NULL ) return( 0 );

DWORD dwBytesWritten = 0;
int i;
for( i=0; i<size; i++ ){
WriteCommByte( buffer[i] );
dwBytesWritten++;
}

return( (int) dwBytesWritten );

}

int CSerial::ReadDataWaiting( void )
{

if( !m_bOpened m_hIDComDev == NULL ) return( 0 );

DWORD dwErrorFlags;
COMSTAT ComStat;

ClearCommError( m_hIDComDev, &dwErrorFlags, &ComStat );

return( (int) ComStat.cbInQue );

}

int CSerial::ReadData( void *buffer, int limit )
{

if( !m_bOpened m_hIDComDev == NULL ) return( 0 );

BOOL bReadStatus;
DWORD dwBytesRead, dwErrorFlags;
COMSTAT ComStat;

ClearCommError( m_hIDComDev, &dwErrorFlags, &ComStat );
if( !ComStat.cbInQue ) return( 0 );

dwBytesRead = (DWORD) ComStat.cbInQue;
if( limit < (int) dwBytesRead ) dwBytesRead = (DWORD) limit;

bReadStatus = ReadFile( m_hIDComDev, buffer, dwBytesRead, &dwBytesRead, &m_OverlappedRead );
if( !bReadStatus ){
if( GetLastError() == ERROR_IO_PENDING ){
WaitForSingleObject( m_OverlappedRead.hEvent,2000 );
return( (int) dwBytesRead );
}
return( 0 );
}

return( (int) dwBytesRead );

}

Hier ist mein Main Funktion:
int main(int argc, char* argv[])
{
char atbefehl[1024]="";
char receive[1024]="";
printf("Hello World!\n");
CSerial port;
if (port.Open(5,9600)==false)
printf("Port kann nicht oeffnen");
else
printf("Port ist geoeffnet\n");
cin>>atbefehl;
// port.SendData(atbefehl,sizeof(atbefehl));

if (port.SendData(atbefehl,sizeof(atbefehl)!=0))
printf("Send Data is sucessful.\n");
Sleep(2000);
//port.Receive(receive,1024);

if (port.ReadData(receive,sizeof(receive))==0)
printf("Read Error");
else
printf(receive);

Sleep(2000);

return 0;
}