Loading google analytics in 1.5.5.1

When I enter my ga code in the systems-settings-server box and hit save, I'm taken to a page that looks like my store and says "page not found". The code is not saved. Any ideas? I've tried it several times, different pc's, different browsers.

Hi,

Conect FTP, go to catalog/view/theme/YOUR_THEME/template/common
open header.tpl and find <?php echo $google_analytics; ?>. Replace it by your GA CODE, save it and upload again

regards