The target computer's shares are unavailable over the network. At a minimum the IPC$ and ADMIN$ shares must be available in order to access the target computer to deploy software, perform inventory scans, or otherwise remotely administer the computer.
Target may not be a Windows computer.
File and Printer sharing may be disabled, a firewall may be blocking access, the shares have been deleted, or there is a name resolution problem. The target system could also be in the process of booting up and access was attempted before the system was completely online.
One possible cause of this error is that the target computer isn't running the Computer Browser service.
Verify that the ADMIN$ share can be accessed on the target computer using Windows Explorer or run the Remote Repair utility.
Follow this link for instructions on how to Enable File and Print sharing on the target computers.