Syncback can't see files on file server

I didn't find something similar on other topics so I hope not a repost.

I am trying to sync a folder on an internal hard disc(left) with a folder on a file server(right).The file server is a usb storage device on a router.

My problem is that syncback doesn't see the files contained in the folder on the file server. It doesn't copy the files from right to left and it constantly overwrites the files from left to right.The same happens when feeding it with an ftp address of the same folder.

Note: that only happens on a pc with windows 7. The same process is working fine on other pcs with windows xp. It aslo works fine when the same sync profile is performed between the windows 7 and xp machines.

Note 2: I ve'had problems accessing the files on the file server from the win7 machine but I worked that issue out be removing the ipv6 protocol. I m guessing it's relevant.

Any tips? I am guessing it has something to do with security issues on win7.