🚀 go-pugleaf

I wrote an app server as an ActiveX library by using C++ Builder 5. In this 
library, I have added a Transactional Data Module, then I implemented a 
function as the following codes:

  STDMETHODIMP TMIDASServer::foo(void)
  {
    ...
    if(...)
      return S_OK;
    else
      return E_FAIL;
  }

On the client side, I added a Data Module, then put a DCOMConnection, a 
ClientDataSet into it. I tried to use the following codes to call this server 
function:

  HRESULT hr;
  hr=DataModule1->DCOMConnection1->AppServer.Exec(Function("foo"));
  if(SUCCEEDED(hr))
    ShowMessage("Succeeded.");
  else
    ShowMessage("Failed.");

The problem is: When the server tries to return S_OK, the client can show the 
message correctly; when the server tries to return E_FAIL, the client raises an 
EOleSysErr exception with the message "Unspecified error". What's wrong with my 
codes?
Another question: I can call the server function as above, is there a similar 
function/method in Delphi 5? If it is, how to do that?
Thanks for any help.

Regards,
George