When the installer accesses a remote location it accesses the location in both the current user and SYSTEM context. You must verify both users have access to the shared directory. You can use the net use command to create sessions in the current context. You can also create a session in the SYSTEM context by using Microsoft's PsExec command to run the net use command in the SYSTEM context.
Note: The net use command only adds the session for the current context.
PsExec allows you to run the command in the SYSTEM context, which then adds the
session in the SYSTEM context.