Most likely you have a blank line of code or space above the redirect. A redirect can't take place once code has been sent to the page and a blank line or even a space counts.
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.