Where you able to do this checklist, i refered this below link when i had similar issue in 8.6. I had issues as the folder path mentioned was incorrect. I believe the path should start with / . if the folder created in sftp is CUCMBACKUP. I mentioned /CUCMBACKUP/
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/drs/8_6_1/drsag861.html#wp42653
Enter the backup device name in the Backup device name field.
Note 
The backup device name may contain only alphanumeric characters, spaces ( ), dashes and underscores (_). Do not use any other characters.
Step 7 Choose one of the following backup devices and enter the appropriate field values in the Select Destination area:
•Tape Device—Stores the backup file on a locally attached tape drive. Choose the appropriate tape device from the list.
Note Be aware that you cannot span tapes or store more than one backup per tape.
Note Be aware that if you are logged in through a VMware virtual machine, you cannot back up on a tape. This is because the tape device option is disabled for VMware users.
•Network Directory—Stores the backup file on a network drive that is accessed through an SFTP connection. DRS only supports SFTP servers that are configured with an IPv4 address or hostname/Fully Qualified Domain Name (FQDN). Enter the following required information:
–Server name: Name or IP address of the network server
–Path name: Path name for the directory where you want to store the backup file
–User name: Valid username for an account on the remote system
–Password: Valid password for the account on the remote system
–Number of backups to store on Network Directory: The number of backups to store on this network directory.
