Resource does not exist when using Xrm.Utility.getResourceString

Hey all, I'm trying to retrieve the translation string with 

Xrm.Utility.getResourceString("trn_/xml/BECalendar", "WorkWeek")

but I get an error:

Uncaught Error: 'trn_/xml/BECalendar' does not exist.

I followed the steps described here: http://howto-mscrm.com/2017/11/dynamics-365-v9-0-string-resx-web-resources-a-better-world-with-localization.html , created the resx file for language English with resource name containing 1033, added the resource as dependency for my JS script but am still getting this error.

Is there anything else I have to set?

Any help is much appreciated!

Regards,

Denis