Painting error on Mac OS ?

When I try to render anything with QImage, QPixmap I get the "<<error>> CGAffineTransformInvert: singular matrix" error.
Platform: Mac OS.
Everything works just fine on a Windows XP or 7 machine, compiled under mscv++2010.

the code:

QImage img(filePath);
...
...
...
QRectF imgRect = QRectF(img->rect());

QPainter p(img);
p.setPen( m_conf.Color ); // some valid QColor object
p.setBrush( Qt::SolidPattern );
p.setFont( m_conf.Font ); // some valid QFont object
p.setOpacity( m_conf.Opacity ); // from 0.0 to 1.0

qreal x = imgRect.width();
qreal y = imgRect.height();

p.save();
p.translate( x, y );
p.rotate(-90);

// Get's error CGAffineTransformInvert: singular matrix.
p.drawText( QPointF(0 + m_conf.BottonMargin , 0 - m_conf.RigthMargin),m_conf.String);

p.restore();