Multisite sign-up / register page redirecting to home

I’m configuring a multisite with all of the recommended plugins and for some reason the registration page will not show: either http://wilderweb.com.au/wp-signup.php or http://wilderweb.com.au/register/ both just go back to the home page. I have mapped the main domain associated with the hosting account from woof.org.au to wilderweb.com.au because the latter is the one I want to be visible everywhere. Have I caused an issue by mapping that domain? Thanks in advance. Sarah