How to get wp-signup.php to work with Anti-Splog

Its driving me crazy and I just can not get the signup page of Anti-Splog to show up correctly.

I tried adding [ust_wpsignup_url] to the url of a menu link item but wordpress automatically added http:// in front making is useless.

I tried adding [ust_wpsignup_url] on a page and adding this page as a menu item but all I see when I press Sign Up on my menu is:

http://mokabox.tv/signup-XXX/ (So the shortcode does get replaced correctly, but I don't want of see the link, I want the page to be loaded.)

I also tried the php code <?php ust_wpsignup_url(); ?> on the same page as above, but the exact same results: the php gets replaced and I see the correct link but not the actual sign up page.

What am I doing wrong?? Argh...