You need to ensure that NetFlow is enabled on your device and set to export its flows to your SolarWinds server on the correct port.
By the sounds of it, either NetFlow isn't configured at all, the exporter isn't configured, the exporter is configured to the wrong IP address, or you have the exporter talking to the server on the wrong port.
In fact if everything went fine, the netflow interface will be AUTOMATICALLY added without manualy adding them, however, here how I would proceed in this order:
- Make sure that netFlow is enabled on that device and it exports to the NMS Server IP_address and correct port (default port is 2055).
- Make sure that no Access-List nor Firewal restriction between the device and the NMS server prevent UDP traffic port 2055.
- If it is still a problem then:
Download and install Wireshark Network sniffer and install it on the NMS Server ( 32 bit or 64 bit)
in the filter filed enter : cflow to filter only NetFlow traffic coming to the NMS Server.
in the Source Address field you should see the IP address of your device if netflow is reaching the NMS Server.
Tell me if it worked or not