When using short year format while reading date from string, resulting QDateTime has year 19xx. This seems strange to me, because most operating systems convert two-digits year to interval 1930-2030.
I suggest at least current DateTime should be 21st century.

QDateTime dtNormal=QDateTime::currentDateTime();
QString strDate=dtNormal.toString("ddMMyyhhmmss");
QDateTime dtFromString=QDateTime::fromString(strDate,"ddMMyyhhmmss");
qDebug(dtNormal.toString("ddMMyyyyhhmmss").toAscii());
qDebug(dtFromString.toString("ddMMyyyyhhmmss").toAscii());