Hi I have a problem with SqlLite database. Here is my code:

void incomeDialog::on_add_pushButton_clicked()
{
int a = ui->income_lineEdit->text().toInt();
int b = ui->other_lineEdit->text().toInt();
int c = (a+b);

db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName("money.db");
QSqlQuery query(db);
query.exec("create table Income"
           "(Month TEXT, Payment NUMBER, Other NUMBER, Together NUMBER)");
query.prepare("INSERT INTO Income values (?,?,?,?)");

query.addBindValue(ui->comboBox->currentText());
query.addBindValue(ui->income_lineEdit->text().toInt());
query.addBindValue(ui->other_lineEdit->text().toInt());
query.addBindValue(c);
query.exec();
}

I use qt sdk 1.0.2. After building shows errors:

Undefined reference to 'QSqlDatabase::addDatabase(QString const&, QString const&)...

all errors is similar (Undefined reference to 'QSqlDatabase::

Do you have any idea how to repair it?