a6bb6589_seUS_Todo_Backup__online_help___Meaning
[Error Codes] 0X*****511 [Error Codes_2] 0X*****602 [Meaning_3] The computer you tried to connect has achieved the limit number of simultaneous users. [Meaning] 
Selected storage path is invalid (Such as: CD/DVD ROM Drive).
Error Code list of EaseUS Todo Backup- online help.
Meaning