Languagesystem arab URD

in one of the Fonts that I work The Menu of languages in this way:

languagesystem DFLT dflt;
languagesystem arab dflt;
languagesystem latn dolt;
languagesystem latn ENG;
languagesystem arab URD;

But the urdu language is not working on Windows system only after deleting the last line of the list of languages!
To become explained below:

languagesystem DFLT dflt;
languagesystem arab dflt;
languagesystem latn dflt;
languagesystem latn ENG;

Any updates pls?