How to connect to ms sql server 2008 EXPRESS？

[csoapy]

the code:

QString error;
    QString conn = "Data  Source=.\\SQLEXPRESS;Initial Catalog=master;Integrated  Security=False;Persist Security Info=False;"
               	"User  ID=sa;password=[]";
 
    QSqlDatabase db =  QSqlDatabase::addDatabase("QODBC", "MainDBConnection");
    db.setDatabaseName(conn);
    db.setUserName("sa");
    db.setPassword("[]");
 
    if  (!db.open())
        error = db.lastError().text();

QString error;
    QString conn = "Data  Source=.\\SQLEXPRESS;Initial Catalog=master;Integrated  Security=False;Persist Security Info=False;"
               	"User  ID=sa;password=[]";

    QSqlDatabase db =  QSqlDatabase::addDatabase("QODBC", "MainDBConnection");
    db.setDatabaseName(conn);
    db.setUserName("sa");
    db.setPassword("[]");

    if  (!db.open())
        error = db.lastError().text();

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but it not works, error == "[Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified QODBC3: Unable to connect"

while following run, when i use mssql 2005 enterprise edition.

conn = QString::fromLocal8Bit("DRIVER={SQL SERVER};SERVER=192.168.10.96;DATABASE=master;Uid=sa;Pwd=[]");
	QSqlDatabase db = QSqlDatabase::addDatabase("QODBC", "MainDBConnection");
	db.setDatabaseName(conn);
	db.setUserName("sa");
	db.setPassword("[]");

conn = QString::fromLocal8Bit("DRIVER={SQL SERVER};SERVER=192.168.10.96;DATABASE=master;Uid=sa;Pwd=[]");
	QSqlDatabase db = QSqlDatabase::addDatabase("QODBC", "MainDBConnection");
	db.setDatabaseName(conn);
	db.setUserName("sa");
	db.setPassword("[]");

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thx!