Hi,

I am using one grid on a silverlight window;

Columns are customly generated and with radio buttons I toggle one data type with different columns in the grid;

Unpredictably, it sometimes throws this exception, usually on the first toggle function:

[Arg_NullReferenceException]
Arguments:
Debugging resource strings are unavailable. Often the key and arguments provide sufficient information to diagnose the problem.
See http://go.microsoft.com/fwlink/?linkid=106663&version=4.0.60831.0&File=mscorlib.dll&Key=Arg_NullReferenceException


 at Infragistics.Controls.Grids.XamGridRowsManager.InvalidateGroupBy(Boolean reset)
   at Infragistics.Controls.Grids.RowsManager.InvalidateData()
   at Infragistics.Controls.Grids.RowsManager.OnColumnLayoutPropertyChanged(ColumnLayout layout, String propertyName)
   at Infragistics.Controls.Grids.XamGridRowsManager.OnColumnLayoutPropertyChanged(ColumnLayout layout, String propertyName)
   at Infragistics.Controls.Grids.RowsManagerBase.OnColumnLayoutPropertyChanged(Object sender, PropertyChangedEventArgs e)
   at System.ComponentModel.PropertyChangedEventHandler.Invoke(Object sender, PropertyChangedEventArgs e)
   at Infragistics.DependencyObjectNotifier.OnPropertyChanged(String propertyName)
   at Infragistics.Controls.Grids.ColumnLayout.InvalidateData()
   at Infragistics.Controls.Grids.ColumnLayout.OnColumnAdded(ColumnBase columnBase)
   at Infragistics.Controls.Grids.ColumnBaseCollection.AddItem(Int32 index, ColumnBase item)
   at Infragistics.Collections.CollectionBase`1.Add(T item)
   at MVVM_Smo.Client.Controls.SMOGrid.SMOGridBase.addColumnsTrivialAction(KeyValuePair`2 p)

please help

thanks