QSqlQuery don't return

[ShadowBelmolve]

Hello, I'm having a strage problem, I'm using Qt 4.6.3 and sqlite 3.7.2 and a certain query return results from sqlite command line but don't return anything from QSqlQuery

The query

SELECT DISTINCT(incomings.id) FROM incomings JOIN incoming_products ON incoming_products.incoming_id = incomings.id WHERE incoming_products.name LIKE '%ar%'

SELECT DISTINCT(incomings.id) FROM incomings JOIN incoming_products ON incoming_products.incoming_id = incomings.id WHERE incoming_products.name LIKE '%ar%'

To copy to clipboard, switch view to plain text mode 

a part of code

QSqlQuery query;
qDebug() << query.exec("SELECT DISTINCT(incomings.id) FROM incomings JOIN incoming_products ON incoming_products.incoming_id = incomings.id WHERE incoming_products.name LIKE '%ar%'");
qDebug() << query.size();

QSqlQuery query;
qDebug() << query.exec("SELECT DISTINCT(incomings.id) FROM incomings JOIN incoming_products ON incoming_products.incoming_id = incomings.id WHERE incoming_products.name LIKE '%ar%'");
qDebug() << query.size();

To copy to clipboard, switch view to plain text mode 

the output

true
-1

true
-1

To copy to clipboard, switch view to plain text mode 

this is the only query of my app that don't work and the only thing I need to finish my app
anybody know why this don't work?