I am afraid there is a bug in this scenario. I have logged it in our public issue tracking system, you can find it and check its resolution here. As a temporary workaround you can convert the DataTable to a list of objects, where only the relevant columns are included and send that list to the SeriesMapping. I have attached a small example showing this.
I have updated your Telerik points for bringing this to our attention.
Best regards,
Ves
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Explore the
Telerik Public Issue Tracking
system and vote to affect the priority of the items