Ein Object in TObjectList<T> löschen mit Ereignis

[RWarnecke]

Hallo zusammen,

ich habe folgende Klassen erstellt :

Delphi-Quellcode:

type
  TModifyActionList = (lnNone, lnAdded, lnChange, lnDelete);

  TDegree = class
  private
    FOnChange      : TNotifyEvent;
    FOnDelete      : TNotifyEvent;
    FModifyAction  : TModifyActionList;
    FID            : Integer;
    FDegree        : string;
    procedure SetID(const Value: Integer);
    procedure SetDegree(const Value: string);
  public
    property ID            : Integer           read FID            write SetID;
    property Degree        : string            read FDegree        write SetDegree;
    property ModifyAction  : TModifyActionList read FModifyAction  write FModifyAction;
    property OnChange      : TNotifyEvent      read FOnChange      write FOnChange;
    property OnDelete      : TNotifyEvent      read FOnDelete      write FOnDelete;
  end;

  TCustomObjectList<T: class> = class(TObjectList<T>)
  private
    FOnChange     : TNotifyEvent;
    FOnDelete     : TNotifyEvent;
    FModifyAction : TModifyActionList;
    FNewRecord    : Boolean;
    procedure DeleteRecord(Klasse: T);
  protected
    function getItem(Index: Integer): T; virtual;
    procedure setItem(Index: Integer; Objekt: T); virtual;
    procedure Notify(const Item: T; Action: TCollectionNotification); override;
  public
    function Add(Objekt: T): Integer; virtual;
    function NewRecord(Objekt: T): Integer; virtual;
    function Remove(Objekt: T): Integer; virtual;
    function IndexOf(Objekt: T): Integer; virtual;
    procedure Insert(Index: Integer; Objekt: T); virtual;
    property Items[index: Integer]: T         read getItem       write setItem; default;
    property ModifyAction : TModifyActionList read FModifyAction write FModifyAction;
    property OnChange     : TNotifyEvent      read FOnChange     write FOnChange;
    property OnDelete     : TNotifyEvent      read FOnDelete     write FOnDelete;
  end;

{...}

{ TDegree }

procedure TDegree.SetDegree(const Value: string);
begin
  FDegree := Value;
  if (Assigned(FOnChange)) and (FModifyAction = lnChange) then
    FOnChange(Self);
end;

procedure TDegree.SetID(const Value: Integer);
begin
  FID := Value;
  if (Assigned(FOnChange)) and (FModifyAction = lnChange) then
    FOnChange(Self);
end;

{ TCustomObjectList<T> }

function TCustomObjectList<T>.Add(Objekt: T): Integer;
begin
  FNewRecord := False;
  Result := inherited Add(Objekt);
end;

procedure TCustomObjectList<T>.DeleteRecord(Klasse: T);
begin
  // To do something  
end;

function TCustomObjectList<T>.getItem(Index: Integer): T;
begin
  Result := T(inherited Items[Index]);
end;

function TCustomObjectList<T>.IndexOf(Objekt: T): Integer;
begin
  Result := inherited IndexOf(Objekt);
end;

procedure TCustomObjectList<T>.Insert(Index: Integer; Objekt: T);
begin
  inherited Insert(Index, Objekt);
end;

function TCustomObjectList<T>.NewRecord(Objekt: T): Integer;
begin
  FNewRecord := True;
  Result := inherited Add(Objekt);
end;

procedure TCustomObjectList<T>.Notify(const Item: T;
  Action: TCollectionNotification);
begin
  if (Assigned(FOnChange)) and (FNewRecord) and (Action <> cnRemoved) then
  begin
    FNewRecord := False;
    FOnChange(Self);
  end;
  if Action = cnRemoved then
  begin
    FOnDelete(Item);
  end;
  inherited Notify(Item, Action);
end;

function TCustomObjectList<T>.Remove(Objekt: T): Integer;
begin
  Result := inherited Remove(Objekt);
end;

procedure TCustomObjectList<T>.setItem(Index: Integer; Objekt: T);
begin
  inherited Items[Index] := Objekt;
end;

Das funktioniert auch alles soweit ganz gut, bis auf den Teil mit FOnDelete. Warum bekomme ich jedesmal bei der Zeile FOnDelete(Item); eine AccessViolation ? Wie kann ich das beheben und was habe ich falsch gemacht ?