Just did a scan of my network, but the screen is blank
If you look under Discovered Nodes on the left side of NTM, do you see anything?
Can you share a screen shot of your setup? I'm interested in seeing what you're trying to scan--if you can ping it from the platform on which NTM is installed, you should see results once the scan has completed. Assuming your display and filtering options aren't getting in the way.
Do you have SNMP setup on all of the devices - and the IP of the NTM allowed to access them?