The problem is that the ItemsSource of the series is expected to be an IEnumerable (or a DataSet). The CustomObject you are passing to it is neither of those and casting does not work, leaving the actual items source a null.
I do not want to make suggestions for you to change your code because of two reasons.
1. You are using the old RadChart. We have a newer control, the ChartView
, which is much much faster, it is very flexible, easy to set up and more interactive. I suggest you completely remove the old RadChart along with the Charting dll which contains it.
2. I am not sure what result you need to get. Depending on how you expect the bars to be visualized, clustered and stacked, the code will be different. If you need further assistance I will ask that you provide us with a snapshot, some drawing, of the output you need.
Again I will suggest that you do not use the old RadChart. It has many limitations that we have eliminated in the new charting solution. I hope that you will be able to migrate to the chart view.