I configured multisite on my site. Whenever I try to access

Hi,

I configured multisite on my site.

Whenever I try to access my primary domain without the "www", it redirects to http://www.myprimarydomain.com/wp-signup.php?new=myprimarydomain.com

If type in "wwww.myprimarydomain.com", it shows my primary site normally, but if I leave out the "www", it redirects to signup.php.