Have you ever entered the country code CH for a shipment to China? How about GE for Germany? Of course CH is the code for Switzerland. GE is the code for Georgia. The correct code for China is CN and for Germany is DE.
Here is a useful link to add to your bookmarks. It includes 2 and 3 letter ISO country codes, international calling codes, and IATA airport codes. Great maps too!
https://www.nationsonline.org/oneworld/country_code_list.htm