Using subversion on an CIFS mounted share

I am setting up an ubuntu svn/apache2 server for our production environment.
Also, it is mandatory, that the actual data is saved on a centralized location in our environment(different server, mounted via smb4).

Problem:

When commiting files from an svn client (testet on Windows and MacOSX) a revision was created and even data was uploaded. But at the end of the committing process, the svn client was throwing an error:

Warning: post commit FS processing had error: Couldn't open rep-cache database '/home/svn/repos/db/rep-cache.db'

I have created other svn repos which were not on an mounted CIFS drive without problems. this error only occurs, when the repo is on the mounted smb share.

Below, you can see my /etc/fstab entry for the svn share and the ownership of the data

//10.0.1.50/virtuelle-DBs/svn-repos /home/svn/ cifs rw,uid=www-data,gid=www-data,file_mode=0775,dir_mode=0775,user=USER,password=PASS 0 0

$ls -la /home/svn/repos
total 1
drwxrwxr-x 2 www-data www-data   0 Jul 21 15:58 .
drwxrwxr-x 2 www-data www-data   0 Jul 21 15:58 ..
-rwxrwxr-x 1 www-data www-data 246 Jul 21 15:58 README.txt
drwxrwxr-x 2 www-data www-data   0 Jul 21 15:58 conf
drwxrwxr-x 2 www-data www-data   0 Jul 22 09:20 db
-r-xr-xr-x 1 www-data www-data   2 Jul 21 15:58 format
drwxrwxr-x 2 www-data www-data   0 Jul 21 15:58 hooks
drwxrwxr-x 2 www-data www-data   0 Jul 21 15:58 locks 

$ls -la /home/svn/repos/db
total 19
drwxrwxr-x 2 www-data www-data  4096 Jul 22 09:20 .
drwxrwxr-x 2 www-data www-data     0 Jul 21 15:58 ..
-rwxrwxr-x 1 www-data www-data     2 Jul 22 09:20 current
-r-xr-xr-x 1 www-data www-data    41 Jul 21 15:58 format
-rwxrwxr-x 1 www-data www-data     5 Jul 21 15:58 fs-type
-rwxrwxr-x 1 www-data www-data 10835 Jul 21 15:58 fsfs.conf
-rwxrwxr-x 1 www-data www-data     2 Jul 21 15:58 min-unpacked-rev
-rwxrwxr-x 1 www-data www-data     0 Jul 21 15:59 rep-cache.db
-rwxrwxr-x 1 www-data www-data     0 Jul 22 09:19 rep-cache.db-journal
drwxrwxr-x 2 www-data www-data     0 Jul 21 15:58 revprops
drwxrwxr-x 2 www-data www-data     0 Jul 21 15:58 revs
drwxrwxr-x 2 www-data www-data     0 Jul 22 09:20 transactions
-rwxrwxr-x 1 www-data www-data     2 Jul 22 09:19 txn-current
-rwxrwxr-x 1 www-data www-data     0 Jul 21 15:58 txn-current-lock
drwxrwxr-x 2 www-data www-data     0 Jul 22 09:20 txn-protorevs
-rwxrwxr-x 1 www-data www-data    74 Jul 21 15:58 uuid
-rwxrwxr-x 1 www-data www-data     0 Jul 21 15:58 write-lock

Did I do something wrong in my fstab? because www-data should have all permissions which are nessessary to edit the rep-cache.db?
I even tried mounting the share with 0777 permissions.

Or does this, perhaps, have to do with SQlite?
Does svn even handle its DBs over sql? My understanding of databases is very shallow.