Server backup failed

[Seth Boon]

I have a local Server running tekkit 2. when I try to backup it says:

/backupsmod backup
[19:32:49] [Server thread/INFO] [minecraft/DedicatedServer]: Started backup
[19:32:49] [Server thread/INFO] [backups]: Starting backup
[19:32:49] [Server thread/INFO] [backups]: Disabling world saving
[19:32:49] [Backup Thread/INFO] [backups]: Flushing world data to disk
[19:32:49] [Backup Thread/INFO] [backups]: Trimming old backups
[19:32:49] [Backup Thread/INFO] [backups]: Creating backup
[19:32:49] [Backup Thread/ERROR] [backups]: Backup failed
java.nio.file.AccessDeniedException: backups\world\In-Progress\advancements
        at sun.nio.fs.WindowsException.translateToIOException(Unknown Source) ~[?:1.8.0_441]
        at sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source) ~[?:1.8.0_441]
        at sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source) ~[?:1.8.0_441]
        at sun.nio.fs.WindowsFileSystemProvider.implDelete(Unknown Source) ~[?:1.8.0_441]
        at sun.nio.fs.AbstractFileSystemProvider.delete(Unknown Source) ~[?:1.8.0_441]
        at java.nio.file.Files.delete(Unknown Source) ~[?:1.8.0_441]
        at silly511.backups.helpers.FileHelper.deleteDirectory(FileHelper.java:53) ~[FileHelper.class:?]
        at silly511.backups.helpers.FileHelper.cleanDirectory(FileHelper.java:44) ~[FileHelper.class:?]
        at silly511.backups.helpers.BackupHelper.backup(BackupHelper.java:57) ~[BackupHelper.class:?]
        at silly511.backups.BackupManager$BackupThread.run(BackupManager.java:223) [BackupManager$BackupThread.class:?]

 

How do I fix this.

thanks in advance