Hi,
this is a problem related to language file for the template. Are you using English as defauld language for your site? If yes, check if the language file of the template is correctly installated. If not, you should create a new language file for your local language.
If you want to use a different language than English, follow these steps:
1) Unzip the template package
2) Open the file en-GB.tpl_gk_postnote.ini and translate it.
3) Rename the file for your local language. Eg: for Italian, it-IT.tpl_gk_postnote.ini
4) Copy the file into the directory for your local language. Eg: for Italian, languageit-IT
Cheers.