with eCart 5, you should install it first, then start and close dreamweaver, then install the other extensions.
When installing a new version of an extensions, you must uninstall the previous version first even if you are installing the same version.
For Example, if you have Data Bridge 1.1.9 installed in the extension manager, and you wish to install it again, you must first uninstall it.
if you have custom presets you wish to save, use the preset manager to export them then import them after installing again.