Updatable ResultSet isn't updatable

Hi!

I want to update a row in an updatable resultset. But SQLException 510
(cursor for file write protected) has been thrown. Displaying the server job
shows, that the db-file was opened read only. Why that?

I'm using the IBM Java Toolbox JDBC 2.0 driver with DB/400 V5R2. Here is my
code:

    DriverManager.registerDriver(new
com.ibm.as400.access.AS400JDBCDriver());
    con = DriverManager.getConnection ("jdbc:as400://.../", "...", "...");
    con.setAutoCommit(false);
    stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,
ResultSet.CONCUR_UPDATABLE);
    rs = stmt.executeQuery("SELECT * FROM AVEFM ORDER BY SRT");
    rs.absolute(row);
    /* Modify some columns */
    rs.updateRow();
    con.commit();

Thanks for any help,

Titus