We have a report which is built with nested data windows and want to change the color of the graph in the graph data window (which is nested in another data window).
1. When using SetSeriesStyle - dw_main.Object.dw_graph.Object.dw_graph1.SetSeriesStyle("gr_1", "Test", NoSymbol!)

But got the error - External object reference
Main window - dw_main  , In the main window included dw_graph and 2 graph data windows dw_graph1 and dw_graph2 added on dw_graph

2. Tried adding child data window for the nested window but did not help.

I am able to do few changes like below 

dw_main.object.dw_graph.object.dw_graph1.object.gr_1.backcolor = rgb(255,0,255)
dw_main.object.dw_graph.object.dw_graph1.object.gr_1.title = "test"

Any help would be appreciated, Thank you