Hi Vignesh,
Thanks for using Syncfusion products.
The StackingGroup feature for stacked type chart is available from Essential studio 8.3 version. So, we suggest you to upgrade the Essential studio to the latest versions to effectively use our Syncfusion products.
http://www.syncfusion.com/support/forums/general/104795/Essential-Studio-2012-Volume-3-Final-Release-v103043-available-for-download
Please let us know if any concerns.
Regards,
Vijayabharathi