Create Favicon with Mac?

Hi-
I’m trying to create a favicon, but when I attempt to install the plugin for Photoshop (e.g., from Telegraphics http://www.telegraphics.com.au/sw/icoformat.en.html), Photoshop says that it couldn’t open because it doesn’t recognize it. Any idea on what I’m doing wrong? Thanks!

Background
Adobe Creative Suite 5
Mac, Intel, OSX 10.8.2, 2.53 GHz Intel Core 2 Duo, 4 GB 1067 MHz DDR3

Hm, I’ve been using that for a long time with no probs in CS5 Mac. There seems to be a newer version on the home page:

How are you trying to install it?

Otherwise, there are online tools for creating a favicon format, such as

http://www.chami.com/html-kit/services/favicon/
http://www.favicon.cc/
http://www.prodraw.net/favicon/index.php

thanks - I’m double-clicking to install it. And funny thing about it is that it appears to be installed because when I check under the Plugins pull-down menu, I see it listed.

Hm, have you closed Ps and opened it again?

That did it. Thanks!