Type mismatch using Mozilla ActiveX in place of Microsoft WebBrowser?

[Noozer]

I've just installed the Mozilla ActiveX control. I'm trying to replace the
Microsoft WebBrowser control with the Mozilla control, but I'm getting a
type mismatch error trying to get the browser document property. The app
worked fine with the WebBrowser control.

'...Sub starts here...
Dim doc as HTMLDocument
Set doc = web.Document ' <- Type mismatch happens here.

Select case doc.URL
'...more code

Is there something that I'm missing here?