You must now be LOGGED IN to the game to suggest a link.
Well, to be more precise, you CAN "suggest a link" without being logged into the game, but those suggestions are ignored and deleted without review. Only suggested links submitted by somebody who is logged into the game are reviewed and approved or disapproved based on their merits...
so remember, when entering your guild's webpage or forum as a new Link to go on the Guild Links section, make sure you are logged in as your character.