MY JAPANESE TRANSLATION FILE OF GLOBAL SITE SEARCH DOESN'T APPLY

Hey
I hope you having a good day.
When I tried to activate the translation file named global-site-search-ja.mo which is the same name, when I downloaded the file from WPMU DEV, it didn't work.

I think the translation's file name is incorrect.

Could you give me any suggestion?

King Regards

KAZUKI