425 Cannot open data connection about node-ftp HOT 4 OPEN

var Client = require('ftp'),
    connects = 0,
    filelist = [];


var srcparams = { // windows FTP Server
    host: "ftptest1.com",
    port: 21,
    user: "ftp",
    password: "password"
};

var destparams = {
    host: "ftptest2.com",
    port: 21,
    user: "ftp",
    password: "password"
};

var src = new Client();

var dest = new Client();

src.on('ready', function() {
    console.log('source ready');
    connects++;
    list();
});

dest.on('ready', function() {
    console.log('destination ready');
    connects++;
    list();
});

src.connect(srcparams);
dest.connect(srcparams);

function DirWalk(dir, prefix, callback) {
    var directory;
    if (prefix !== undefined || prefix !== '') {
        directory = prefix + '/' + dir;
    } else {
        directory = dir;
    }
    src.list(directory, function(err, dirlist) {
        if (err) {
            console.log(err);
        }
        callback(null, directory, dirlist);
    });
}

function toDirList(files, prefix) {
    if (prefix === undefined) {
        prefix = '';
    }
    for (var b in files) {
        files[b].path = prefix;
        filelist.push(files[b]);
        if (files[b].type === 'd') { // is a directory
            files[b].path = prefix;
            DirWalk(files[b].name, prefix, function(err, prefix, dirlist) {
                if (dirlist.length > 0) {
                    toDirList(dirlist, prefix);
                }
            });
        } else if (files[b].type === '-') {

        }
    //console.log(filelist);
    }
}

function list() {
    if (connects === 2) {
        src.list(function(err, list) {
            toDirList(list);
        });
    }
}