Hi Naveed,
We could see this issue. If we try to create a Table object on Page events will always holds null value for Table object.
GridGroupingControl1.TopLevelTable will returns the System.Web.UI.WebControl.Table only when the GridRow corresponds to the display elements (i.e return the Elements the get rendered in Grid row such as sequence of templates).
Attached is the sample which illustrate the usage scenario of "TopLevelTable".
http://websamples.syncfusion.com/samples/Grid.Web/5.1.0.0/DT60305/GridGroup_Forum60305/main.htmIn our sample, we have Edited the all rows in GridGroupingControl at a time and created a Table dynamically to get access the affected values of display elements which get rendered in Grid rows.
Let us know if you need any other assistance.
Thanks for using Syncfusion products.
Regards,
Gokulkumar B