Why does CFile::modeWrite reset my file content?

[j.a.z]

Hi

I can't figure out what the problem is.
In my last post some users suggested me to use the CStdioFile for reading a whole line. That works FINE! I used the same Object to Write a file with the method WriteString. That works but the problem is i'd like to append Text in a file. However when i open the file with CFile::modeWrite and append data with WriteString the content of the file will be reseted to 0.

It is documented that when i use "CFile::modeWrite | CFile::modeCreate" the file will be reseted but only the CFile::modeWrite should not reset the file to 0?

What's my failure?

Thank you.
jaz

void CLogAppWndDlg::OnOK()
{
    // TODO: Add extra validation here
    CStdioFile fStream;
    CString strBuffer;

    UpdateData(TRUE);

    strBuffer = m_tDatePicker.Format("%Y.%m.%d\t%a\t%H:%M:%S");
    strBuffer = strBuffer + "\t" + m_strTxt + "\t" + m_strComment + "\n";

    if( !fStream.Open(m_strLogFile, CFile::modeWrite, NULL) )
    {
        if( !fStream.Open(m_strLogFile, CFile::modeWrite | CFile::modeCreate, NULL) )
        {
            MessageBox("Open or Create of LogFile faild!\nFile: " + m_strLogFile,"Error");
            return;
        }
    }

    fStream.WriteString(strBuffer);  :confused: 
    fStream.Close();

    CDialog::OnOK();
}