wrong selection mechanism on class reimplemented from QTableWidget

i reimplemented QTableWidget.
Now for example, i selected row number 5.
Then i'm changing current item like this(on 8):
SelectionModel->setCurrentIndex(Model->index(8,0),QItemSelectionModel::NoUpdate);
Then if i'm trying to add selection with shift key (from 8 to 10).
Now i have a problem - I need to select 8, 9 and 10 items, but selection made from 5 to 10.
Please help
best regards Arsen