SQLITTE "unable to fetch row"

[giusepped]

I have two database connections (SQLITE).
The second one is created by:

bool MainWindow::createConnection(const QString &id)
{
	databasePanels = QCoreApplication::applicationDirPath()+"/panels.db";
 
	QSqlDatabase db =  QSqlDatabase::addDatabase("QSQLITE",id);
 
	db.setDatabaseName(databasePanels);
	db.open();
/ 
	if (db.isOpen())
		return true;
	else
 
		return false;
}

bool MainWindow::createConnection(const QString &id)
{
	databasePanels = QCoreApplication::applicationDirPath()+"/panels.db";
 
	QSqlDatabase db =  QSqlDatabase::addDatabase("QSQLITE",id);
	
	db.setDatabaseName(databasePanels);
	db.open();
/ 
	if (db.isOpen())
		return true;
	else
	
		return false;
}

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void MainWindow::createTablePanel(const QString &type)
{
	QSqlDatabase db=QSqlDatabase::database(type);
	db.setDatabaseName(databasePanels);
	QSqlQuery q(db);
	q.prepare(" create table pannelli ( id INTEGER NOT NULL PRIMARY KEY,costruttore VARCHAR(50),modello VARCHAR(50),pnom  )");
	q.exec();
 
}

void MainWindow::createTablePanel(const QString &type)
{
	QSqlDatabase db=QSqlDatabase::database(type);
	db.setDatabaseName(databasePanels);
	QSqlQuery q(db);
	q.prepare(" create table pannelli ( id INTEGER NOT NULL PRIMARY KEY,costruttore VARCHAR(50),modello VARCHAR(50),pnom  )");
	q.exec();
 
}

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but I get:

createTablePanel.: QSqlError(-1, "Unable to fetch row", "No query") "

why?