Sql-delete works only in Simulator

[Matze5590]

Hello,

i have a sqlite database in my project. alle the data in the database is shown in a QTableView.
When i select a row and press a "delete"-Button this row should be deleted.
everything works fine with Simulator, but on device(Nokia N8) nothing happens.
Any idea why?

Here my code:
@QTextStream(&str_del) << "DELETE FROM Table WHERE ID = " << index.row() << ";";
if (query_ges.exec(str_del) == false){
QSqlError err = query_ges.lastError();
if (err.number() != 1){
QMessageBox::warning(this, "Error", err.text(), "Ok");
}@
When i debug the Statement looks like that:
"DELETE FROM Table WHERE ID = 1;"
and no error occures.

[Matze5590]

i dont know why, but when i set the ID as "NOT NULL PRIMARY KEY" everything works fine, also on device!