Register missing on attacment.php

[rockerzteam]

My forum is missing the following line that's at the bottom of that image that says register here? How do I add that and where?

The administrator may have required you to register before you can view this page.

Code missing!

<div class="smallfont">The administrator may have required you to <a href="register.php?do=signup" rel="nofollow">register</a> before you can view this page.</div>

Where do I add that.