The error indicates that the reference to the connection file is not correct.
Please make sure that you have a Connections folder on the save level as your Admin folder, and ensure you have a localhost.php file in your Connections folder.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.