I have already replied to the support ticket that was opened by you on the matter, so that I paste my answer there for the community:
Most probably there is something wrong with the returned data. Can you please try to extract this chart's data source and then provide it back to us, so that we can make an examination?
The easiest and fastest way to export the chart data source is to utilize the client-side API. For example:
You can also export the data source on the server-side - convert SqlDataSource to a DataTable data source and then extracted it to an XML file.
sender, EventArgs e)
//How to convert the SQLDataSource to a DataTable:
//DataSourceSelectArguments args = new DataSourceSelectArguments();
//DataView view = (DataView)SQLDataSource1.Select(args);
//DataTable dt = view.ToTable();
DataTable dt = GetData();
RadHtmlChart1.DataSource = dt;
dt.TableName = DataTableName;
i = 0; i < dt.Columns.Count; i++)
dt.Columns[i].ColumnMapping = MappingType.Attribute;