Robocopy - NTFS Access is Denied

I am trying to backup a disk from one share to another using robocopy with the following command:

robocopy \\servername\E$ \\servername\F$\Copy /E /ZB /copyall /r:5 /w:30 /dcopy:T /log:"C:\Temp\log.log" /v /fp /tee /eta

However whenever I try to execute the command (with Admin privileges), I get the following error:

ERROR 5 (0x00000005) Copying NTFS Security to Destination Directory \\servername\F$\Copy
Access is Denied.

Now the NTFS permissions for the user logged in has full control, as well as the Administrator account on both shares (E and F). I am running the command from a Windows 2012 server and pointing the source/destination to a Windows 2003 server (which I cannot run the following robocopy command as its an older version). The share is fully accessible from the W2012 server, therefore this should not be the problem.

I have already looked at this question which has not solved my issue as I already have the /ZB parameter.

The robocopy command was perfect. It turns out that the F:\ drive which is located at nas3, does not like multiple connections at once.

Therefore the solution was too:

1. iSCSI unmount F:\ on the W2003 machine
2. iSCSI mount F:\ on the W2012

The command ran perfectly after the changes.