i get this error and killing my time to find solution. the instalation is really not clear from step to step. and the file in tracking module 2.3 is not complete.
The solution for this error is u need to open the read me file for ur tracking module like dhl for example. u unzip it and open the readme inside.
and u will see step no6.
Edit catalog/includes/languages/german/tracking_module.php, and before the closing ?>, ADD
Then add the below code to the languages. save and upload to server. Done. error gone!
New 
