To fix this, you need to enable Passive mode for your connection to the server.
- Choose the Site menu, then Manage Sites
- Select the site you're trying to connect to and choose Edit
- Check the box marked Use passive FTP
- Click the OK button
All set! Try connecting again.
For these instructions including screenshots, check out the following help doc on TigerTech: http://support.tigertech.net/dreamweaver-passive