sql backup error

Hi

when i want get backup from SQL DB i see this error:

Unable to attach to a resource. Make sure that all selected resources exist and are on-line, and then try again. If the server or resource no longer exists, remove it from the selection list. Edit the selection list properties, click the View Selection For additional information regarding this error refer to link V-79-57344-33932

i use a backup to disk folder method and create a folder in backup server

this error shows when i want get a backup server from SQL server but when i get backup file "no DB" my job is successfully

how do i solve this problem