Re: How to solve this question?

Hello all:
      I write a component using ATL and it includes two interface:ISMath and
IAMath,
and now I write client codes and want to the file tlb,Look:
#import "Com_01.tlb" no_namespace
#include <windows.h>
#include <iostream.h>

void main()
{
   HRESULT hr;
   hr=CoInitialize(NULL);
    if(FAILED(hr))
 {
  cout<<"Initialize COM failed"<<endl;
        return;
 }

   ISMathPtr spSFun;
   IAMathPtr spAFun;
   spSFun.CreateInstance(L"Com_01.SMath");
   long s=spSFun->Add(11,12);
   cout<<s<<endl;
   spSFun.QueryInterface(IID_IAMath,spAFun);//It displays this sentence is
error
   s=spAFun->Sub(22,11);
   cout<<s<<endl;
   spSFun.Release();
   spAFun.Release();
   CoUninitialize();}

I compile and it displays: 'IID_IAMath' : undeclared identifier,why?how to
do?
Thanks very much.