If you're using the "Scan for New Nodes", it's possible there aren't enough events generated in the timeframe we're scanning for to conclusively discover your device. You might need to manually configure it instead (from Manage > Appliances, left Gear on the appliance -> Connectors).
You might also try toward the end of the day after it's been sending events for a while, there might be more data then. If we need to, we can dig in to determine which connector to configure, or whether this is the case.