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What version of Dreamweaver are you using?
Double check that preview has not been disabled. Go to Edit -> WebAssist Preferences, in the preview section, make sure the disable option is not selected.
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.