make sure that you have enabled the search API in your google account and that you have created the search engine.
see this tutorial for details:
http://www.webassist.com/tutorials/Getting-started-with-Google-Search
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.