Bro i use window xp not window 7 :/like i said your firewall of anitvirus may be blocking it so try adding WTFast into exception list of blocked programes
edit:here's how you can add exception program
http://www.sevenforums.com/tutorials/542-windows-firewall-add-remove-exception.html
Yea latest version bro.is that the latest version? or try to download the latest version of it.