Footer Template

[Black Snow]

I am trying to do a str_replace in the footer so my edit shows up on every page but vB doesn't seem to like it. The function works fine on every page as long as it's not in the footer.

Is there a way to do this on all pages or is there a more simple way to str_replace in the footer?
Example

    $vbulletin->templatecache['FORUMHOME'] = str_replace($find, $replace, $vbulletin->templatecache['FORUMHOME']);