I had the same problem. Fix as follows:
->Turn Windows features on or off
->Internet Information Services
->World Wide Web Services
->Application Development Features
->enable ISAPI Extensions
Then try adding the script map again.
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.