Good Luck with this, it worked for me and I consider it luck! lol
I copied the link found for the countdown clock and changed the dates according to my cruise. The only additional thing I did was added [url[ at the beginning of the link and [/url] at the end of the link.
Then I pasted it in my signature line and it worked. Hope it works for you too.
Something so simple that stumps so many people! Have a great cruise.