Common Issue 1: Variables are not replaced in the order confirmation page source code
Check that there not {literal} around the tag
<script type="text/javascript">
_kkstrack = {
...
Common Issue 2: Wrong template
You need to edit the correct file to implement Kelkoo Sales Tracking. Please verify which file you have edited.
Common Issue 3: Cache has not been refreshed
Whenever you make a change in your file, you need to refresh your cache. Go to your Admin panel > Advanced > Performance > Refresh cache