Error when adding a new nfs (backup) device

[HENNES-X]

Dear all
I tried to add an additional backup device on my "Virtual Environment 8.3.2" system via pvesm.

PVESM returns allways with the following error:

mkdir /mnt/pve/VE-BACKUP02/images: Read-only file system at /usr/share/perl5/PVE/Storage/Plugin.pm line 1516. (500)

Has anybody an idea what is going wrong here ? Any ideas to resolve this issue ?

Thanks
Uli