Group By working properly, but whenever I attempt to collapse a group it does nothing the first time, then after collapses only one row. 

The client-side error comes from ScriptResource.axd line 4157

current group settings:

detailGrid.GroupingSettings.EnableColumnGrouping = Infragistics.Web.UI.DefaultableBoolean.True;
detailGrid.GroupingSettings.GroupAreaVisibility = Visibility.Visible;
detailGrid.DataKeyFields = "Category";
detailGrid.GroupingSettings.GroupedColumns.Add("Category");
 detailGrid.GroupingSettings.GroupedColumns.Add("Reason");