Robocopy - Backup between network computers

I am trying to use Robocopy to perform a backup on a daily basis and only update files which have either been updated, or they are new files.

At the moment I am using the following script within a Batch file:-

@ECHO OFF

SETLOCAL

SET _source="\\REMOTE-SERVER\Share"

SET _dest="\\LS-WXLDE8\Shared_QP"

SET _what=/COPYALL /B /SEC /MIR
:: /COPYALL :: COPY ALL file info
:: /B :: copy files in Backup mode. 
:: /SEC :: copy files with SECurity
:: /MIR :: MIRror a directory tree 

SET _options=/R:0 /W:0 /LOG:MyLogfile.txt /NFL /NDL
:: /R:n :: number of Retries
:: /W:n :: Wait time between retries
:: /LOG :: Output log file
:: /NFL :: No file logging
:: /NDL :: No dir logging

ROBOCOPY %_source% %_dest% %_what% %_options% /MOT:1440

At the moment I am getting the following messages within my log file:-

-------------------------------------------------------------------------------
   ROBOCOPY     ::     Robust File Copy for Windows                              
-------------------------------------------------------------------------------

  Started : 10 December 2014 09:51:11
2014/12/10 09:51:13 ERROR 5 (0x00000005) Getting File System Type of Destination \\LS-WXLDE8\Shared_QP\
Access is denied.


   Source : \\REMOTE-SERVER\Share\
     Dest - \\LS-WXLDE8\Shared_QP\

    Files : *.*

  Options : *.* /NDL /NFL /S /E /DCOPY:DA /COPY:DATS /PURGE /MIR /B /MOT:1440 /R:0 /W:0 

------------------------------------------------------------------------------

NOTE : NTFS Security may not be copied - Destination may not be NTFS.

ERROR : You do not have the Backup and Restore Files user rights.
*****  You need these to perform Backup copies (/B or /ZB).

ERROR : Robocopy ran out of memory, exiting.
ERROR : Invalid Parameter #%d : "%s"

ERROR : Invalid Job File, Line #%d :"%s"


  Started : %s %s

   Source %c 

     Dest %c 
       Simple Usage :: ROBOCOPY source destination /MIR

             source :: Source Directory (drive:\path or \\server\share\path).
        destination :: Destination Dir  (drive:\path or \\server\share\path).
               /MIR :: Mirror a complete directory tree.

    For more usage information run ROBOCOPY /?


****  /MIR can DELETE files as well as copy them !

I'm trying to backup from a Windows 8 Computer to a Buffalo Link Station Duo (NaS Drive) - I've allowed users / guests / admins on that folder for full permissions (read/write), can't find anywhere where you can add 'Network' privileges on the control panel, there is no option to add user groups.

Any ideas?

You don't have the right user permissions to access the directory.