[DevExpress Support Team: CLONED FROM T343862: ASPxSpreadsheet - The "System.InvalidOperationException" error is thrown when the SetSolidFill method is executed]
you can not use a secondary axis if the ranges are built against a set of dates for the x-axis. If you try to, the series placed on the secondary axis will not be rendered.
running the code produces a set of 4 charts, which I'll place in the next comment so you can quickly see what I'm talking about. All 4 charts use the same data, but differ as to how the secondary axis is handled and the use of dates for the x-axis.
if you have any suggestions/work-arounds, etc. they would be most appreciated. This is a show-stopper for our client.
Thank you