Fireworks and Extension Manager don't see each other

I have Fireworks CS5 Version 11.0.0.484.

I have Extension Manager CS5.5 Version 5.5.163.

All this on OSX Snow Leopard.

Fireworks isn't listed in Extension Manager.

From within Fireworks, when I go to Commands -> Manage Extensions..., nothing happens.

When I double-click on an MXP file containing a Fireworks extension, I get "This extension cannot be installed, it requires Fireworks version 9 or greater."

What are the troubleshooting steps I should follow?