Verification won't appear on multisite

I just installed your plugin on a blog that is part of a multisite network.

Though the admin works fine, the verification does not show up at all, even on a browser where I am not logged in and with cookies cleared.

I see that the stylesheet is loaded and some styles are output but that is all, no trace of the form itself.

http://ww.wp.xz.cn/extend/plugins/age-verify/