Label/legend from a stream data field possible?

I have fields from Azure Stream Analytics. They plot fine on a line graph but I can't seem to use any of the fields as the Legend. In fact the Legend input "drag any field here" is disabled? I get a field "deviceID" with every reading. The deviceID is always the same for this stream. I need to display this deviceID somewhere on the line graph, e.g in legend or title, since it is part of the data. I don't want a line in the graph with the same (always) deviceID on it since it is not a measurement.

Thanks for tips!