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You shouldn't be editing footer.php in the root of your XOOPS installation. That file is responsible for wrapping up the processing of the XOOPS environment and getting everything written to the screen.
Rather, what you want to do is edit the default theme (preferably, copy the default theme to a new theme and edit that instead). At the bottom of "\xoops\themes\default\theme.html" is a section devoted to the footer for every XOOPS output page. This is where you should put anything that you'd like to show up in your page's footer.
Also, if you don't see the new stuff show up right away, then you might try clearing out the "\xoops\tempaltes_c" folder, which contains cache data for your various pages.
Hope this helps...