QSqlTableModel t;       
//  configure  db, filter etc.    .........................
t.select();
QSqlRecord rec=t.record();  // get an empty record
//  fill the record fields with values .............
if(t.recordCount())   // only count = 1 is possible because of my logic
     t.setRecord(0,rec);
else
   t.insertRecord(0,rec);
t.submitAll();

The insertRecord part works always .
The setRecord part only t works if I change a least one boolean field in the record to the opposite value which is stored currently in the DB. Then the text field changes to new values too.
But If I change only a text field no changes will be transmitted to the DB.
I get no error, all seem to work but nothing changes in the DB.

It seem that Qt "thinks" that the record has not changed and skip the storing ?
Can this be ?
Why is there a difference betweent bool and string values ?

How can i fix the problem ?