To reproduce:

1. Populate RadGridView with data
2. Export the grid by using the SpreadExport
3. Open the produce Excel file and select  some cells to generate a chart in Excel. You will notice that it is not possible to create a complete chart with the selected data.

Workaround: use the ExportToExcelML >> http://www.telerik.com/help/winforms/gridview-exporting-data-export-to-excel-via-excelml-format.html