This is what arcserve recommends. PROBLEM: E8523 Failed to send data to the client agent.
RESOLUTION: If you want to backup using the agent, the best route to take is to go through the agent tree, this will backup the drives and not the shares. You can also go through the network, but only selecting the drive(s) and the registry, and then choosing use agent, this will also bypass the shares on the machine. If you need to backup your entire machine, shares and all, you have to go through network, without selecting to use the agent. Also always make sure that the agent is running. To check this go to the machine running the client agent- Go to Start\programs\ARCserve client agent for Windows NT / Windows 95. Go to Agent services, make sure the agent is either running or enabled, and the bottom of the GUI should say waiting for connection. If you are running the client agent for Windows 95, you should add the agent into the startup group, the 95 agent does not use services, It is an executable, and the only way to stop/start the agent is to reboot the 95 machine. You can also check to see If the agent is responding by going to a Dos Prompt and typing in: telnet 6050. If the telnet popup box comes back It means the agent is active and responding, If you do not get a box, there is no connection to the agent.
Also make sure you test your login rights by right clicking on the object, putting in domain\userid and password. Then go to expand the agent object. If you can expand it you can back it up.