Wordfence Backup Failure

I have received the following backup failure message – How can I rectify this?
“6th May 2014 9.46.01 AM Error A filesystem operation failed while processing ‘Filesystem/public_html/wp-content/uploads/2014/01/My-Movie-1.wmv’ (Size unknown) for backup.
If the following error message is not clear as to the problem and the issue persists, please contact support providing the complete event log for the activity. Diagnostic information follows:

Failed at: 1045(/home/sortyour/public_html/wp-content/plugins/wponlinebackup/include/files.php)
Attempt to write to file /home/sortyour/public_html/wp-content/plugins/wponlinebackup/tmp/gzipbuffer.c5e518f8a258a32294d84fac1d030343291400c0.php only partially succeeded. Only 4730833 of 8388608 bytes were written. (16777216 bytes already written.) PHP last error: No error message was logged.
6th May 2014 9.45.19 AM Information Folder /public_html/wp-content/plugins/wponlinebackup/tmp was excluded: Temporary backup directory
6th May 2014 9.43.50 AM Information Folder /public_html/wp-content/backups was excluded: Local backups directory
6th May 2014 9.43.43 AM Information Database backup completed.
6th May 2014 9.43.36 AM Information Initialisation completed.
6th May 2014 9.43.36 AM Information Ignoring comments that are marked as spam.
6th May 2014 9.43.36 AM Information Ignoring comments in the trash.
6th May 2014 9.43.36 AM Warning Table ‘wp_wfStatus’ has no PRIMARY or UNIQUE key! Backup of this table may be inconsistent; some rows could get missed. See FAQ for more information.
6th May 2014 9.43.36 AM Warning Table ‘wp_optimizepress_launchfunnels_pages’ has no PRIMARY or UNIQUE key! Backup of this table may be inconsistent; some rows could get missed. See FAQ for more information.
6th May 2014 9.43.35 AM Information Backup starting…”