I have a similar issue as this, but that fix did not work for me.

When I use www.bunkerama.com it allows you to log in but does not reflect that after the redirect. When I use bunkerama.com it works fine. This is the code that I pasted into .htaccess:

Options +FollowSymLinks
RewriteEngine on
RewriteCond %{HTTP_HOST} ^bunkerama\.com
RewriteRule ^(.*)$ http://www.bunkerama.com/$1 [R=permanent,L]

Any help?