Recovery Manager for Active Directory Error 101(Unable to perform request)

Hello, 

I have a server Quest Recovery Manager for Active Directory. On some of my servers, I have the error "Failed to connect to backup agent : Unable to perform Request (101). The target computer is busy processing requests started on the computer 'Server which is the Quest recovery Manager for AD". Please try again later."

I view that these servers which have this error had the box checked n the part Local Storage --> "Save backups on the recovery manager computer". And other which worked properly didn't have it.

But after uncheck them, I have the same error. Do you know how I can resolve this error, please ?

Thanks in advance.