Hi Asit,
I apologize for the delay in responding.
Attached is a sample which will help to get the 'Trace' when the 'BarButtonItem' of the Grid Grouping control is clicked.
http://www.syncfusion.com/Support/user/uploads/Forum_64784_94054853.zipTo get the Trace you have to set the 'EnableCallbacks' property of the Grid Grouping control to 'False'.
Please let us know if this helps you.
Regards,
Valli