[PROBLEM] How to automate daily update of library?

[lessger]

I am using Moodeaudio on a Raspberry Pi with HifiBerry. My muisc library is on a Synology NAS connected via Wifi.

The whole setup works fine.

I now want to automate the update of the music library so that changes are incorporated automatically.

I have enabled cron on the pi and defined a daily job to update the library. I tried to update using 

Code:

mpc -w update
   or
mpc -w rescan
   or
curl http://<hostname>/command/cmd=update

All three comands work from the command line interface (user: pi, no error messages). cron activates the script, as I can see from the logfile. I also tried the commands directly from the shell.

With mpc rescan, I verified afterwards with

Code:

mpc listall

and saw that new files were added tp the database.

With all three commands, when I login to moodeaudio later, new files in the library are not shown. When I do update from Configure>Library>update
it works fine.

Can anyone give me a hint what I am doing wrong?

Thank you,
Gerhard