QPSQL driver not loaded Qt

Question

I have some trouble when I want to add a database.

    _dataBase = QSqlDatabase::addDatabase(\"QPSQL\");

After calling this method I have

Answer 1

Add the system variable QT_DEBUG_PLUGINS=1 if you want to get full information of why the QPSQL driver has not been loaded.

Probably you will discover that Qt is not able to find it. Copy and paste the output here to know what exactly happens.