i wanted when the master record in edit mode and the detail table will auto expanded
i followed the example to check in prerender's grid item in edit and set to item.expanded = true
For Each item As GridDataItem In grdClaims.MasterTableView.Items
If item.Edit Then
item.Expanded = True <--- error "There was a problem extracting DataKeyValues from the DataSource. please ensure that DataKeyNames are specified correctly and all the fields specified exist in the datasource"
is there any problem to my code?