What’s the permission error exactly and which account are you using? My understanding is that you are copying files between two domains in a cross forest trust. The account you're using should have permissions in both domains. Try give each
domain admin control of the opposite domain. Then add each domain admin to the group that has full control over the folder containing the files you are copying. Then, try use domain admin to copy files again.
TechNet Subscriber Support |If you have any feedback on Technet forum, please contact firstname.lastname@example.org.
Microsoft is conducting an online survey to understand your opinion of the Technet Web site. If you choose to participate, the online survey will be presented to you when you leave the Technet Web site.