Invalid Pointer Operation

[csander]

Динамически создаю дерево VirtualTreeView внутри CategoryPanel:

...
type
  PPhoneNode = ^TPhoneNode;
  TPhoneNode = record
    Name: String;
  end;
  TForm1 = class(TForm)
...
    procedure FormCreate(Sender: TObject);
    procedure PanelCreate(title: String; numRec: Integer);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure VTGetText(Sender: TBaseVirtualTree; Node: PVirtualNode;
      Column: TColumnIndex; TextType: TVSTTextType; var CellText: string);
    procedure VTFocusChanged(Sender: TBaseVirtualTree;
      Node: PVirtualNode; Column: TColumnIndex);
    procedure VirtualStringTree1FreeNode(Sender: TBaseVirtualTree;
      Node: PVirtualNode);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
var
  Form1: TForm1;
  activeVT : TVirtualStringTree;
  k: Integer;
implementation
{$R *.dfm}
//Создание панели с деревом----------------------------------
procedure TForm1.PanelCreate(title: String; numRec: Integer);
var
  i,j: Integer;
  Panel:  TCategoryPanel;
  Tree:   TVirtualStringTree;
  NewNode, NewNode1 : PVirtualNode;
  NewPhone: PPhoneNode;
begin
  Panel:=PanelGroup.CreatePanel(Self) as TCategoryPanel;
  Panel.Caption:=title;
  PanelGroup.CollapseAll;
  Tree := TVirtualStringTree.Create(Panel);
  Tree.OnGetText := VTGetText; //метод для вывода текста
  Tree.OnFocusChanged := VTFocusChanged;
  Tree.OnFreeNode := VirtualStringTree1FreeNode;
  Tree.Name := 'Name';
  Tree.Parent := Panel;
  Tree.Align := alClient;
  Tree.NodeDataSize := SizeOf(TPhoneNode);
  for i := 1 to numRec do
  begin
    NewNode := Tree.AddChild(Tree.RootNode);
    NewPhone := Tree.GetNodeData(NewNode);
    if Assigned(NewPhone) then
    with NewPhone^ do
    begin
      Name := Query1.Fields.FieldByNumber(1).Value;
//Заполнение типов расчета -----------------------------------------------------
      Query2.SQL.Clear;
      Query2.SQL.Add('select [Тип] from ['+title+'] group by [Тип]');
      Query2.ExecSQL;
      Query2.Active := true;
      if Query2.RecordCount > 0 then
      begin
        for j := 1 to Query2.RecordCount do
        begin
          NewNode1 := Tree.AddChild(NewNode);
          NewPhone := Tree.GetNodeData(NewNode1);
          if Assigned(NewPhone) then
            with NewPhone^ do
            begin
              Name := Query2.Fields.FieldByNumber(1).Value;
            end;
            if j <> Query2.RecordCount then Query2.FindNext;
        end;
      end;
//------------------------------------------------------------------------------
      if i <> numRec then Query1.FindNext;
    end;
  end;
  Panel.InsertControl(Tree);
  k:=k+1;
end;
//-----------------------------------------------------------------------------
//Определяем активное дерево
procedure TForm1.VirtualStringTree1FreeNode(Sender: TBaseVirtualTree;
  Node: PVirtualNode);
var
 Data: PPhoneNode;
begin
 Data := Sender.GetNodeData(Node);
 if Assigned(Data) then
  Finalize(Data^);
end;
procedure TForm1.VTFocusChanged(Sender: TBaseVirtualTree;
  Node: PVirtualNode; Column: TColumnIndex);
begin
  activeVT := Sender as TVirtualStringTree;
  Label1.Caption := activeVT.Text[activeVT.FocusedNode,0];
end;
//-----------------------------------------------------------------------------
procedure TForm1.VTGetText(Sender: TBaseVirtualTree; Node: PVirtualNode;
  Column: TColumnIndex; TextType: TVSTTextType; var CellText: string);
var
  PhoneNode: PPhoneNode;
begin
  PhoneNode := Sender.GetNodeData(Node);
  if Assigned(PhoneNode) then
    CellText := PhoneNode.Name;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
//activeVT.DeleteNode(activeVT.FocusedNode);
activeVT.DeleteSelectedNodes;
end;
procedure TForm1.Button2Click(Sender: TObject);
var
  NewNode: PVirtualNode;
  NewPhone: PPhoneNode;
begin
  NewNode := activeVT.AddChild(activeVT.FocusedNode);
  NewPhone := activeVT.GetNodeData(NewNode);
  if Assigned(NewPhone) then
    with NewPhone^ do
    begin
      Name := 'b';
    end;
end;
procedure TForm1.FormCreate(Sender: TObject);
var
  i:Integer;
  name: string;
begin
k:=0;
Query.SQL.Clear;
Query.SQL.Add('select [Name] from [Организации]');
Query.ExecSQL;
Query.Active := true;
if Query.RecordCount > 0 then
begin
  Query.First;
  for i := 1 to Query.RecordCount do
  begin
    name := Query.Fields.FieldByNumber(1).Value;
    Query1.SQL.Clear;
    Query1.SQL.Add('select [Год] from ['+name+'] group by [Год]');
    Query1.ExecSQL;
    Query1.Active := true;
    PanelCreate(name,Query1.RecordCount);
    if i <> Query.RecordCount then Query.FindNext;
  end;
end;
end;
end.

все создается как надо, но при закрытии формы, выходит ошибка :
Invalid Pointer Operation
не могу никак понять, где ошибка? может где-то надо освободить память?