If you do a search for a well known name on GoDaddy, such as fox.com, youtube.com, google.com, etc., you'll see that the options for .com, .net and others have a red X graphic and say "not available" instead of displaying the usual "backorder now" box. How did those companies get that to happen? Even if you paid for the longest registration period, that box would not show up for your domain. Just a question out of curiosity!
Not sure but it's possible that they've blocked the backorder now box feature for particularly those domain names which are protected with trademark.
Godaddy only allows one backorder per domain through their service. If somebody else has backordered through godaddy then it will show as not available. There are numerous threads on DP about this already.