Filemanager problem with Apache alias

Dear FCKeditor users,

I have a site with two languages: dutch and english.

The dutch site is located at http://www.sitename.nl, the english site is located at en.sitename.nl

I have one upload folder for both sites, in the main (dutch site).

I have two cms systems for the two languages.

The FCKeditor config.php for the dutch site includes
```
$Config['UserFilesPath'] = '/upload/' ;
```

The absolute path is empty and the filemanager works without problems.

I have included an alias in the vhost.conf for the en subdomain, so to use /srv/www/vhosts/sitename.nl/httpdocs/upload/ as /upload/ within the subdomain. Looks like this:
```
Alias /upload /srv/www/vhosts/sitename.nl/httpdocs/upload
<Directory /srv/www/vhosts/sitename.nl/httpdocs/upload>
Order allow,deny
Allow from all
</Directory>
```

I used the same config.php on the english version, because of the alias.

Now the tricky part!

I think I did it correctly, because I can open http://www.sitename.nl/upload/1.jpg and also en.sitename.nl/upload/1.jpg.

BUT if I try to open the filemanager within FCKeditor within my english cms, it cannot open/read the upload folder and I get this error:

Error creating folder "/srv/www/vhosts/sitename.nl/httpdocs/upload/" (Can't create directory)

The upload directory has CHMOD 775 and I even set it to 777 just to see if it would do anything.
I am simply not able to get this fixed, so I would really appreciate any help.

Update

I checked the version of my FCKeditor and I recognized it was nog 2.6.6 but some earlier version of 2.6.x.
So I updated and now the error changed:

Error creating folder "/srv/www/vhosts/sitename.nl/httpdocs/upload/images/" (mkdir(): open_basedir restriction in effect. File(/srv) is not within the allowed path(s): (/srv/www/vhosts/sitename.nl/subdomains/en/httpdocs:/tmp))

Shouldn't open_basedir play any role in this case?! I really don't get it.

Thanks in advance!