Close. On some computers, the "http://" that is in the pop-up box isn't highlighted, so you need to delete it before you copy in the new address. Otherwise, you end up with two "http://" strings in the address text, and it won't be a real address.
A little hint...preview your post before you put it up. That way, you can test it out yourself.

[Yeah, I was being a smart alec.]