I don't know where you got that, I was told by 
my postal clerks as well as the USPS.COM web site
that there is NO TRACKING on Global Priority.:




Q. Can I track my Global Priority Mail package?

A. Express Mail International Service (EMS) and 
Priority Mail Global Guaranteed (PMGG) are the 
only international services that the United States 
Postal Service offers with a tracking capability.
As a more economical service, Global Priority Mail
does not have this feature.