I'm debugging an issue for an old application. 

It uses an ultraGrid and has the following code to setup editorsettings:

            DefaultEditorOwnerSettings editorSettings = null;

            // Add an item for editing date.
            editorSettings = new DefaultEditorOwnerSettings( );
            editorSettings.DataType = typeof( DateTime );
            //editorSettings.MaskInput = "mm/dd/yyyy";
           
            //editorSettings.MaskDataMode = Infragistics.Win.UltraWinMaskedEdit.MaskMode.IncludeBoth;
            editor = new DateTimeEditor( new DefaultEditorOwner( editorSettings ) );
            editorsValueList.ValueListItems.Add( editor, "Date" ).Tag = editor;

In the UltraGrid InitializeRow event, there is the following code to set the editor to a Date Editor:

int index = editorsValueList.FindStringExact( fieldType );

EmbeddableEditorBase editor = null;
            if (index >= 0)
                editor = (EmbeddableEditorBase)editorsValueList.ValueListItems[ index ].Tag;

            e.Row.Cells[ "Value" ].Editor = editor;

This results with the following UI:

Everything looks fine, but when I click on the down arrow for the date editor, the application crashes.

Here is my stack trace:

6/11/2010 : Object reference not set to an instance of an object.
   at Infragistics.Win.UltraWinMaskedEdit.EditInfo.MinValueForMask(Object minValue, String mask)
   at Infragistics.Win.UltraWinMaskedEdit.EditInfo.CalculateTrueMinValue()
   at Infragistics.Win.MonthDropDown.DoDropDown(EmbeddableUIElementBase element)
   at Infragistics.Win.DateTimeEditor.DoDropDown()
   at Infragistics.Win.EmbeddableEditorBase.DropDown()
   at Infragistics.Win.DateTimeEditorDropDownButtonUIElement.OnMouseDown(MouseEventArgs e, Boolean adjustableArea,

UIElement& captureMouseForElement)
   at Infragistics.Win.ControlUIElementBase.ProcessMouseDownHelper(Object sender, MouseEventArgs e)
   at Infragistics.Win.ControlUIElementBase.ProcessMouseDown(Object sender, MouseEventArgs e)
   at Infragistics.Win.Utilities.ProcessEvent(Control control, ProcessEvent eventToProcess, EventArgs e)
   at Infragistics.Win.UltraControlBase.OnMouseDown(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Any thoughts as to why this is crashing?