Where does GUI_GET_REGVALUE fetch the file name from?

Hello Experts,

I have a customized FM which is used for displaying Help.

In this the std FM  GUI_GET_REGVALUE fetches a launcher file name in the format: C:\Users\john.doe\SapWorkDir.

CALL FUNCTION 'GUI_GET_REGVALUE'

         EXPORTING

              ROOT           = HKEY_LOCAL_MACHINE

              KEY            = REGKEY_SAPWORKDIR

              VALUE_NAME     = REGVALUE_SAPWORKDIR

         CHANGING

              STRING         = LAUNCHER_FILENAME

         EXCEPTIONS

              REGISTRY_ERROR = 1

              OTHERS         = 2.

For some users, however this FM does not return any file path.

Are we required to maintain such a path somewhere or is it based on a file SapWorkDir saved in the C drive?

Please advise as several persons are reporting this similar issue.

Thanks in advance.

Cheers,

Peter