Hello everybody

I would like to disable the SSL redirection when trying to checkout .
I tried to do this through :
$mainframe = JFactory::getApplication();
$mainframe->redirect(JRoute::_('index.php?option=com_virtuemart&view=cart&task=editshipment',$this->useXHTML,$this->useSSL), $_retVal);
break;
}
}
if ($cart->getInCheckOut()) {
$mainframe = JFactory::getApplication();
$mainframe->redirect('index.php?option=com_virtuemart&view=cart&task=checkout');
}
}
But no, results. Please help me and thank's a lot