Hi Yacinus,
Thanks for posting your query to us.
We afraid that we are not able to reproduce the issue. Please refer to the following steps that we tried to reproduce it.
* We bind the Grid to AccessDataSourceControl using the DataSourceID.
* We invoked this.DataBind() in the Page_load event.
* And then we tried to loop through the Grid Record and used the SetValue method for the index specified.
Also we have create a simple sample to test this issue and it is available in the following link.
http://websamples.syncfusion.com/samples/Grid.Web/5.1.0.51/F63481/GridGroupingControl_Forum63481/main.htmPlease have a look at the above sample and if still the issue exists, Could you please try reproducing it in the above sample or send us the reproducing steps so that we could sort out the cause of the issue and provide you a soultion.
Regards,
Gokulkumar B