Time Machine over SMB: backupd failed to create Volume, error 20

I am getting an error when trying to backup with time machine to a smb share.

The share is correctly detected by Time Machine and set as destination.

The output of tmutil shows:

====================================================

Name          : FileVault

Kind          : Network

URL           : smb://user@host._smb._tcp.local/FileVault

Mount Point   : /Volumes/FileVault

ID            : BE7DF7B5-8497-4791-BE1B-B002A81FFEFE

When I then try to do the first backup I get an error in console telling me:

Failed

to create

'/Volumes/com.apple.TimeMachine.FileVault-4A9358A9-70D2-4BC1-8D5D-38F09D696563/75A144D6-7B39-5919-B406-828DB9FF6C7A.sparsebundle',

results: {

}, error: 13 permission denied

It seems as if the mount oint is wrong since /Volumes/FileVault/com.apple... would be correct and not /Volumes/com.apple...

Is there a bug or am I doing something wrong?

Edit: it is error 13 not 30 as mentioned in the topic.