Language statement for "onum" & "lnum" features?

Hello there,
Does anyone tell me why I can't make it work "onum" and "lnum" feature for the language for "Latn TRK".
I am trying to write it for a typeface which is written in old FEA. I know I have to Update feature syntax to FEA 2.5. when I open an old fonts but it doesnt work after all.
By the way, it works in the preview panel in Fl. but doesnt work in In design.
Am I doing something wrong? Below are the syntaxes...

This is the original syntax without language TRK statement.

feature onum { # Oldstyle Figures
 script grek; # Greek
    sub @onum1 by @onum2;
 script cyrl; # Cyrillic
    sub @onum1 by @onum2;
 script latn; # Latin
    sub @onum1 by @onum2;
} onum;

This is the new syntax update with FEA 2.5 that I wrote for "language TRK" statement.

feature onum { # Oldstyle Figures
 script DFLT ;
    sub @onum1 by @onum2;
script grek; # Greek
    sub @onum1 by @onum2;
 script cyrl; # Cyrillic
    sub @onum1 by @onum2;
 script latn; # Latin
    sub @onum1 by @onum2;
        language TRK ;
} onum;