`open -a` results in an "Unable to find application" error on OS X

I would like to create a shortcut in my .profile file in OS X Lion to launch the iWork program "Numbers".

The application is in:

/Applications/iWork '09/Numbers.app

I created this shortcut:

alias psd="open -a Adobe\ Photoshop\ CS3"

It works fine to open Photoshop. So I created:

alias num="open -a iWork\ \'09/Numbers"

When I type "num" I get an error:

Unable to find application named 'iWork '09/Numbers'.

I don't think it's a problem of backslashes before the space or the quote because I have tried countless variations to no avail. I also tried adding ".app" to the application name, but got the same error message.

How can I create this alias?

Have you considered the following?

open -a Numbers

Applications opened by open aren't opened relative to their path, but just according to their actual name, as identified in Contents/Info.plist in the .app file itself.

If you want to be sure, you can also use the Bundle Identifier with the -b option:

open -b com.apple.iTunes

Which can be found in the Info.plist file too: