QXmlQuery, fail to open local xml file

[marceloarguello700]

QXmlQuery, fail to open local xml file
Hi i need to open a local xml file and retrieve information,

But i dont can´t.
this is my code:

void xmlFileRead::fileQuery(QString filename)
			{
				QStringList  strList;
				QFileInfo fi(filename);
				qDebug()<< "absPath:"<< fi.absoluteFilePath();
				QXmlQuery query;
				QString q=QString("doc('%1')/systems/string()").arg(fi.absoluteFilePath());
				query.setQuery(q);
				if (query.isValid())
				{
					qDebug()<< "isValid()==true:";
					query.evaluateTo(&strList);
				}

				qDebug()<< "strList:"<< strList.count() ;

			}

and this mi outpup:
absPath: "D:/shapes/98092902.xml"
isValid()==true:
Error FODC0002 in d:/shapes/98092902.xml: Protocol "d" is unknown,
d is the hard drive not a protocol,
I know that is a beginner question, but
Why there are so few samples of QXmlQuery?