passport js returns authentication false despite using right username-password

To be more specific: if i once enter wrong username-password, after that any new attempt with the correct username-password leads to authentication:false

My code:

passport.use(new LocalStrategy(
    function(username, password , done) {    
        User.findOne({ username: username , password:password }, function(err, user) {
            if (err) { return done(err); }
            if (!user) {
                console.log('cannot find username and password');
                return done(null, false);

            }
            return done(null, user);
        });
    }
));

app.post('/login',  function (req,res) {       
    passport.authenticate('local');       
    if(req.isAuthenticated()){
        req.session.destroy();
        res.redirect('/index_connected.html')
    } else{
        req.session.destroy();
        res.redirect('/login.html?code=11820')
    }
});

First thought that deleting previous session might work. But even adding ' req.session.destroy()', nothing new. Thanks in advance

via nick314