Ok, it says u need to collect 20 dogtags to unlock the trophy. As of now i have

Under the Service Record - General Tab - Combat

Dog Tags = 826
Kills = 800

and trophy still hasn't unlocked. I've unlocked the Modern Art trophy. i have the retriever equipped so dogtags are collected automatically. Do you have to collect specific/unique dogtags to unlock this trophy.
Can someone please help.

Thanks in advance