QTableView field (related to other db table) does not get refreshed

Panoss

The articlesTable (a QTableView) displays data from db table 'articles'.
The field 'positions' is related to table 'positions'.
The code:

// Create the data model for articles:
 model = new QSqlRelationalTableModel();
 model->setEditStrategy(QSqlTableModel:: OnFieldChange);
 model->setTable("articles");
 model->select(); 

 // Remember the indexes of the columns:
 positionIdx = model->fieldIndex("position");

 // Set the relations to the database table 'positions':
 model->setRelation(positionIdx, QSqlRelation("positions", "id", "name"));

 // articlesTable is a QTableView, set it's model
 ui.articlesTable->setModel(model);

The problem:
-I add a new record in database table 'positions'
-I call model->select()  (to refresh articlesTable)
-the new record is not displayed in the combo box of field 'positions'

I must close the form and reopen it in order for this field to display the new record.
How can I fix this?