Hiding the second data series of a spread chart

[john hamon <jhamon@xxxxxxxxxxx>]

Thanks for all the help that I've received so far -- so here's another
question:

I want to be able to hide the second data series of a spread chart, so that
I simply have the primary chart and the spread indicator down below it.
When I try to use the "format symbol" dialog to use a hidden subgraph for
the second data series,
the spread indicator stops working -- apparently it can't "see" the data
unless it's on the chart.

I don't really care how I accomplish it, but I would like visually to
conceal the second price series, as I'm using it to produce the spread
indicator and don't actually want to look at it.

I would really appreciate it if anyone can tell me how to do that.

Thanks,

jh