Hi Martin, If your using the latest stable prestashop version 1.3.5.0 you shouldnt need to copy header.php to root, at least i didnt need to. Basically if your using the latest version you can ignore the first zip posted since that was for an older version, download the second zip posted, unzip and copy the two files to your /blockcart/ folder. If you've already replaced your files id suggest starting over with a fresh set of blockcart modules or if you have a backup use that. Also, remember my blockcart.tpl is modified so you may be better of making the changes manually as posted above.