This can happen for several reasons, but I've listed the
most common ones below:
(1)Check to make sure that the target computer is on and
that it is connected (pingable) to the network. Duh!
(2) If you've verified the above, it may be that the
computer you are using to do the backups is not able to
authenticate to the server whose data you are trying to
backup. If you want to backup network shares, you have to
use a network/domain account that has the right to log on
to other machine across the network. You can't use a local
machine user account to do this. The local user's SID is
associated with the local machine. The domain computers
only trust users who have a domain SIDs affixed to their
user and group security isentifiers. This is only possible
with domain user acounts. Also, check the event log on the
target machine, and look for any messages regarding logon
failures, and check out the user name that it references.
If the second scenario describes your problem, you can
resolve this by making sure that you are using a domain
account (I assume your network is a domain model), and
that the account has the right to logon to all the
machines that need to be backed up.
Hope this helps.
