Error in setting a CALLBACK function in a simple Delphi code

Hi, I want to set up a CALLBACK function in a delphi code so that from a C++ dll I can call it; As of now I wrote following code:

program Project1;

{$APPTYPE CONSOLE}

uses
  Windows;
var
    fnSomeDllMethod:procedure() cdecl;
    m_hDll: HMODULE;
type
TCALLBACKPROC = function(arg:Pointer):HRESULT stdcall;
type
TSetCallbackFunc = procedure(_proc:TCALLBACKPROC) cdecl;

var
fnSetCallback:TSetCallbackFunc;

function CallbackProc(wEvent:DWORD;arg:Pointer;pParam:Pointer):HRESULT stdcall;
begin
         MessageBoxA(0,'delphi', 'delphi',MB_OK);
end;

begin
  { TODO -oUser -cConsole Main : Insert code here }

  begin
      begin
        m_hDll := LoadLibrary('DLLMsgBox.dll');
        fnSetCallback := GetProcAddress(m_hDll,'DisplayInMessageBox');
        fnSetCallback(CallbackProc);
        FreeLibrary(m_hDll);
      end;
  end;

end.

It is giving error as :[Error] Project1.dpr(30): Incompatible types: 'Pointer' and 'Cardinal'

Can any one help me?

Thanks

Tags: C++, Delphi