Samba Share is mounted and shows indexing enabled, but why doesn't work?
Since nobody answers this question, I posted what I found so far. 

(1) Spotlight and command line tools tag, mdfind won't work on samba network drive.

(2) To search filename and tag, Finder app works. Finder --> open the samba network drive folder --> In search bar, type filename or tag:tagname, it works very well.