[求助]小弟愚昧，不知道这个错误是怎么回事？

我在界面上放了一个pagecontrol控件，在上面建了3个界面tabsheet。
第一个界面上放了20来个edit控件、1个panel控件。
为了保持和第一个界面的位置一致，我用复制的方法。在第二个界面里粘贴了这些控件，问题就出来了。
调试的时候，出现这个错误：
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Debugger Exception Notification
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Project Project1.exe raised exception class EOleException with message '标准表达式中数据类型不匹配。'. Process stopped. Use Step or Run to continue.
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OK   Help   
---------------------------unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ComCtrls, StdCtrls, Buttons, DB, ADODB, Grids, DBGrids, ExtCtrls,
  ImgList;type
  TForm1 = class(TForm)
    PageControl1: TPageControl;
    TabSheet1: TTabSheet;
    TabSheet2: TTabSheet;
    TabSheet3: TTabSheet;
    Edit1: TEdit;
    Label1: TLabel;
    GroupBox1: TGroupBox;
    Edit2: TEdit;
    Label2: TLabel;
    Label3: TLabel;
    Edit3: TEdit;
    Label4: TLabel;
    Edit4: TEdit;
    Label5: TLabel;
    Edit5: TEdit;
    Label6: TLabel;
    Edit6: TEdit;
    Label7: TLabel;
    Edit7: TEdit;
    Label8: TLabel;
    Edit8: TEdit;
    Label9: TLabel;
    Edit9: TEdit;
    Label10: TLabel;
    Edit10: TEdit;
    Label11: TLabel;
    Edit11: TEdit;
    Label12: TLabel;
    Edit12: TEdit;
    Label13: TLabel;
    Edit13: TEdit;
    Label14: TLabel;
    Edit14: TEdit;
    Label15: TLabel;
    Edit15: TEdit;
    Label16: TLabel;
    Edit16: TEdit;
    Label17: TLabel;
    Edit17: TEdit;
    CheckBox1: TCheckBox;
    Memo1: TMemo;
    BitBtn1: TBitBtn;
    BitBtn2: TBitBtn;
    ADOConnection1: TADOConnection;
    ADOQuery1: TADOQuery;
    DataSource1: TDataSource;
    ADOConnection2: TADOConnection;
    ADOQuery2: TADOQuery;
    DataSource2: TDataSource;
    Panel1: TPanel;
    DBGrid1: TDBGrid;
    ComboBox1: TComboBox;
    ComboBox2: TComboBox;
    Label18: TLabel;
    ADOQuery3: TADOQuery;
    DataSource3: TDataSource;
    Label19: TLabel;
    Edit18: TEdit;
    Label20: TLabel;
    Label21: TLabel;
    ComboBox3: TComboBox;
    ADOTable1: TADOTable;
    DataSource4: TDataSource;
    Label22: TLabel;
    DateTimePicker1: TDateTimePicker;
    Edit20: TEdit;
    ComboBox4: TComboBox;
    ImageList1: TImageList;
    ComboBox5: TComboBox;
    ComboBox6: TComboBox;
    Label23: TLabel;
    Label24: TLabel;
    Edit19: TEdit;
    GroupBox2: TGroupBox;
    Label25: TLabel;
    Label26: TLabel;
    Label27: TLabel;
    Label28: TLabel;
    Label29: TLabel;
    Label30: TLabel;
    Label31: TLabel;
    Label32: TLabel;
    Label33: TLabel;
    Label34: TLabel;
    Label35: TLabel;
    Label36: TLabel;
    Label37: TLabel;
    Label38: TLabel;
    Label39: TLabel;
    Label40: TLabel;
    Label41: TLabel;
    Label42: TLabel;
    Label43: TLabel;
    Label44: TLabel;
    Edit21: TEdit;
    Edit22: TEdit;
    Edit23: TEdit;
    Edit24: TEdit;
    Edit25: TEdit;
    Edit26: TEdit;
    Edit27: TEdit;
    Edit28: TEdit;
    Edit29: TEdit;
    Edit30: TEdit;
    Edit31: TEdit;
    Edit32: TEdit;
    Edit33: TEdit;
    Edit34: TEdit;
    Edit35: TEdit;
    Edit36: TEdit;
    CheckBox2: TCheckBox;
    Memo2: TMemo;
    Edit37: TEdit;
    ComboBox7: TComboBox;
    DateTimePicker2: TDateTimePicker;
    Edit38: TEdit;
    ComboBox8: TComboBox;
    Panel2: TPanel;
    DBGrid2: TDBGrid;
    BitBtn3: TBitBtn;
    BitBtn4: TBitBtn;
    procedure FormCreate(Sender: TObject);
    procedure Edit1Change(Sender: TObject);
    procedure DBGrid1DblClick(Sender: TObject);
    procedure BitBtn1Click(Sender: TObject);
    procedure Edit19Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;
  var dwbh:integer;
implementation{$R *.dfm}procedure TForm1.FormCreate(Sender: TObject);
begin
          edit1.Text:='';
          edit2.Text:='';
          edit3.Text:='';
          edit4.Text:='';
          edit5.Text:='';
          edit6.Text:='';
          edit7.Text:='';
          edit8.Text:='';
          edit9.Text:='';
          edit10.Text:='';
          edit11.Text:='';
          edit12.Text:='';
          edit13.Text:='';
          edit14.Text:='';
          edit15.Text:='';
          edit16.Text:='';
          edit17.Text:='';
          edit18.text:='';
          combobox4.ItemIndex:=0;
          combobox3.ItemIndex:=0;
          edit20.Text:='';
          memo1.Text:='在此添加备注！';
          panel1.Hide;
                                                  //修改表单
          edit19.Text:='';//去掉这一行，调试，就没有错误提示。我纳闷怎么回事呢？？end;//兰色的错误指针指着这里！！！！！！！！！！！！！！！！！！！！！！