Calculate Total in Footer of Nested GridView in ASP.Net

Hello. Can someone help me in binding the Remarks label as footer in my second gridview.

Heres the image 

I set the DataKeyName of the Parent gridview to EmpNo and LeaveTraId, I wanted to pull those datakeys up to include in my query getting the value Remarks field from database.

I used OnRowDataBound event of parent grid to populate the second grid.

if  uhave any easier suggestions to achieve this, that will be so much appreciated!

Thanks,

Bob