Often, post services change the format of the provided data, or new post services are added.
For automaticall update services in App, just switch on following option in menu: "Settings" -> "Postal Services" -> "Auto update postal services". You can also tap on "Check for services updates now."
If, for some reason, auto update does not work, you can go to News section of Forum on this site, and download the services.dat.new file, and then copy it to following folder: "/sdcard/TrackChecker_Mobile". After that, App should be restarted to apply the update of service descriptions. If services are successfully updated, the services.dat.new file should disappear from folder "/sdcard/TrackChecker_Mobile".
Since version v2.19.10, you just may tap on the downloaded services.dat.new file.