一个简单的动态装载DLL测试程序，请LD们看看咋回事？

Question

unit TestDll;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;type
  TForm1 = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
    Label2: TLabel;
    Edit2: TEdit;
    ComboBox1: TComboBox;
    Label3: TLabel;
    Edit3: TEdit;
    Label4: TLabel;
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
  TMultiplyNum=procedure;
var
  Form1: TForm1;
  MultiplyNum:TMultiplyNum;
  theHandle:THandle;implementation
function PlusNum(a,b:integer):integer;stdcall;external 'dll1\project1.dll';
function MinusNum(a,b:integer):integer;stdcall;external 'dll1\project1.dll';
//function MultiplyNum(a,b:integer):integer;stdcall;external 'dll2\project1.dll';
{$R *.DFM}procedure TForm1.Button1Click(Sender: TObject);
begin
  case ComboBox1.ItemIndex of
  0: Edit3.Text :=IntToStr(PlusNum(StrToInt(Edit1.text),StrToInt(Edit2.text)));
  1: Edit3.Text :=IntToStr(MinusNum(StrToInt(Edit1.text),StrToInt(Edit2.text)));
  2: //Edit3.Text :=IntToStr(MultiplyNum(StrToInt(Edit1.text),StrToInt(Edit2.text)));
  begin
    theHandle :=LoadLibrary('E:\test\testDll\dll2\project1.dll');
    if theHandle<>0 then
    begin
      @MultiplyNum:=GetProcAddress(theHandle,'MultiplyNum');
      if @MultiplyNum<>nil then
      begin
        TMultiplyNum(MultiplyNum);
        FreeLibrary(theHandle);
      end;
    end;
  end;
  end;
end;
end.问题1：调用MultiplyNum函数的时候，调试状态下，在FreeLibrary(theHandle)后报地址冲突的错误，直接运行则自动退出程序
问题2：TMultiplyNum(MultiplyNum);这句话应该怎么理解，如果直接换成MultiplyNum；好像效果是一样的。

Answer 1

if @MultiplyNum<>nil then
      begin
        TMultiplyNum(MultiplyNum);
        FreeLibrary(theHandle);
      end;
改为
if @MultiplyNum<>nil then
      begin
        MultiplyNum(参数);
      end;
    FreeLibrary(theHandle);

Answer 2

tomboy0(小波波) 
应该不是这个原因，这个函数是调用一个MessageBox,用不到传入的参数，如果我不用动态装载的方式，而是象PlusNum，MinusNum那样直接调用是没有问题的。

Answer 3

unit TestDll;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;type
  TForm1 = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
    Label2: TLabel;
    Edit2: TEdit;
    ComboBox1: TComboBox;
    Label3: TLabel;
    Edit3: TEdit;
    Label4: TLabel;
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
  TMultiplyNum=function(a,b:integer):integer;stdcall;
var
  Form1: TForm1;
  MultiplyNum:TMultiplyNum;
  theHandle:THandle;implementation
function PlusNum(a,b:integer):integer;stdcall;external 'dll1\project1.dll';
function MinusNum(a,b:integer):integer;stdcall;external 'dll1\project1.dll';
//function MultiplyNum(a,b:integer):integer;stdcall;external 'dll2\project1.dll';
{$R *.DFM}procedure TForm1.Button1Click(Sender: TObject);
begin
  case ComboBox1.ItemIndex of
  0: Edit3.Text :=IntToStr(PlusNum(StrToInt(Edit1.text),StrToInt(Edit2.text)));
  1: Edit3.Text :=IntToStr(MinusNum(StrToInt(Edit1.text),StrToInt(Edit2.text)));
  2: //Edit3.Text :=IntToStr(MultiplyNum(StrToInt(Edit1.text),StrToInt(Edit2.text)));
  begin
    theHandle :=LoadLibrary('E:\test\testDll\dll2\project1.dll');
    if theHandle<>0 then
    begin
      @MultiplyNum:=GetProcAddress(theHandle,'MultiplyNum');
      if @MultiplyNum<>nil then
      begin
        TMultiplyNum(MultiplyNum);
        FreeLibrary(theHandle);
      end;
    end;
  end;
  end;
end;
end.