Mail Keyboard Shortcut for Add Hyperlink...

I added Control Option H as a new shortcut for Add Hyperlink in the Mail pull down menu
It showed up in the Keyboard Shortcuts list and also shows correctly in the pull down menu after I quit and re-opened Mail; however when I try the shortcut, nothing happens.
Could it be that I have to take into account pulling down the Edit menu first, to get to the Add Hyperlink command?
And it only works after I create a New Message.
How do I do all this?
Thanks....David