The logon processor did not add the message alias.
Any action to correct the problem should be performed on that computer. Your user name is already established as a message alias. Either your user name and computer name are the same, or your user name is in use as a message alias on another computer on the network. If your user name is being used as a message alias on another computer, you cannot receive messages at the local workstation using this name.
If your user name is being used as a message alias on another computer, delete the alias on that computer. Then log on again at this computer.