The GridView is empty

Question

Hi all, I need your appreciated help.

I try this code: 
http://www.c-sharpcorner.com/UploadFile/718fc8/how-to-show-record-into-gridview-using-dropdownlist-in-web-a/

In my attachment code I don't have error but the GridView is empty. 

Can you help me?
Thanks in advance.