This application scans the computers in the network based on various fingerprints. They're called so because when a SQL server is running, it broadcasts packets on the network or it has open ports with specific numbers. The software works in the same way as NMAP does. It uses custom packets to detect SQL versions and operating systems.
If no servers are found on the network, then it means:
There are actually no servers on the network.
The firewall on the network prevents discovery packets to be sent over the Intranet and you have to contact the local Administrator for further diagnostics.