If you have multiple versions of Adobe (or Macromedia) software installed, you probably have multiple versions of Extension Manager, the application that helps you install and manage extensions. This can lead to some confusion.

When you double-click an MXP (or ZXP) file, your operating system open your default version of Extension Manager. This may not be the version that you want, however. Suppose you have Flash Pro CS4 and Flash Pro CS5 installed. Your system will (probably) automatically launch Extension Manager CS5 when you attempt to install a new extension. This is okay if you want to install the extension in Flash CS5, but it will not be available in Flash CS4.

There are other issues that crop up when you have versions installed in multiple languages (and in some cases, if your language is not English). Luckily, there’s a simple way ensure that you’re using the correct version of Extension Manager.

1. Launch the version of Flash Pro (or Dreamweaver, or Fireworks) in which you’d like to install the extension.
2. Go to Help > Manage Extensions… and it will launch the matching installation of Extension Manager.