non-www to www redirect htaccess

I have a little problem and I don't know why is that.

I tried :

RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

and

RewriteCond %{HTTP_HOST} ^domain.com [NC]
RewriteRule ^(.*)$ http://ift.tt/1dx3YFa [L,R=301]

But no succes.

It redirect the website from : http://domain.com to http://www.domain.com but not from http://ift.tt/1WErBD9 to http://ift.tt/Pc3zCg

Why?!