Expandable rows in datagrid view not working c#

Question

 sir

 

http://www.c-sharpcorner.com/UploadFile/deveshomar/expandable-and-collapsible-rows-in-datagrid-in-C-Sharp-winforms/

I implemented thecode from the above mentioned link  but i am not able to get the child or expandable rows. Kindly help me.