Help! Unable to Decrypt

Trying to decrypt my external drive and after an hour, it gives me the message that it can't be done,and to see the log. Here's what the log says:
Images - Protected/A to G/BRITNEY SPEARS/.ML101_21r_BritneySpears.tif.iFlhZX" failed: Permission denied (13)
Jan 13 16:38:37 Macintosh-249 com.taoeffect.EspionageHelper[4756]: rsync: mkstemp "/Volumes/Mark Liddell Archive BACKUP DRIVE/Marc Liddell Images - Protected/A to G/BRITNEY SPEARS/.ML101_22_BritneySpears.tif.1mo9e8" failed: Permission denied (13)
Jan 13 16:38:37 Macintosh-249 com.taoeffect.EspionageHelper[4756]: rsync: mkstemp "/Volumes/Mark Liddell Archive BACKUP DRIVE/Marc Liddell Images - Protected/A to G/BRITNEY SPEARS/.ML101_24_BritneySpears.tif.ZbTiSq" failed: Permission denied (13)
Jan 13 16:43:10 Macintosh-249 rsync[7913]: open on A to G/BRITNEY SPEARS/large/3803: No such file or directory
It goes on like that for pages for all the files. It's either "No such file" or "Permission denied"
Please - I need to know how to decrypt the drive!
Images - Protected/A to G/BRITNEY SPEARS/.ML101_21r_BritneySpears.tif.iFlhZX" failed: Permission denied (13)
Jan 13 16:38:37 Macintosh-249 com.taoeffect.EspionageHelper[4756]: rsync: mkstemp "/Volumes/Mark Liddell Archive BACKUP DRIVE/Marc Liddell Images - Protected/A to G/BRITNEY SPEARS/.ML101_22_BritneySpears.tif.1mo9e8" failed: Permission denied (13)
Jan 13 16:38:37 Macintosh-249 com.taoeffect.EspionageHelper[4756]: rsync: mkstemp "/Volumes/Mark Liddell Archive BACKUP DRIVE/Marc Liddell Images - Protected/A to G/BRITNEY SPEARS/.ML101_24_BritneySpears.tif.ZbTiSq" failed: Permission denied (13)
Jan 13 16:43:10 Macintosh-249 rsync[7913]: open on A to G/BRITNEY SPEARS/large/3803: No such file or directory
It goes on like that for pages for all the files. It's either "No such file" or "Permission denied"
Please - I need to know how to decrypt the drive!