Yellowcat - Have you solved your problem yet?

You say you can copy files as root, so that suggests a setup problem at the linux end.

What mount options are you using to mount the samba - I think this is likely to be where the problem is.

Try going into user management and set up a group called 'samba' and record the GID for this group (lets say its 505)

Then in the mount options for mounting the drive (or in fstab) use gid=505,umask=007

Finally add the users you want to have read/write access to the samba group.

HTH

Steve