[GD-Windows] OLE Automation

[Dave S. <dav...@sd...>]

Problem:

I'm using C++ OLE Automation to send data to a MS Excel Spreadsheet.
I'm trying to call Invoke on an IDispatch and I keep getting an unknown
exception.
The objects come from the excel8.olb type library.

Does anybody here know of links, newsgroups, or places to ask
such questions?

Details:

The interface I'm trying to call in Excel is on the IValidation, Add method.
The .olb defines it as such:

[id(0x0000000b5), ....]
void Add(
                   [in] XlDVType  Type,
                   [in, optional] VARIANT AlertStyle,
                   [in, optional] VARIANT Operator,
                   [in, optional] VARIANT Formula1,
                   [in, optional] VARIANT Formula2);

For my example, only the Type, AlertStyle, and Formula1 are necessary.  The
others
are not used.

My c++ code is as follows:

const wchar_t *stupidstr = L"this,is,a,retarded,interface";

   hr = pValidation->GetIDsOfNames( IID_NULL, &szAdd, 1, LOCALE_USER_DEFAULT,
&dispID );
   if ( SUCCEEDED(hr) )
   {
      VARIANTARG  vargs[5];
      DISPPARAMS  dp = { 0, 0, 0, 0 };

      VariantInit( &vargs[4] );
      const int xlValidateList = 3; // from the OLE type lib excel8.olb
      vargs[4].vt = VT_I4;
      vargs[4].lVal = xlValidateList;

      VariantInit( &vargs[3] );
      const int xlValidAlertStop = 1;
      vargs[3].vt = VT_I4;
      vargs[3].lVal = xlValidAlertStop;

      VariantInit( &vargs[2] );
      vargs[2].vt = VT_ERROR;
      vargs[2].scode = DISP_E_PARAMNOTFOUND;

      VariantInit( &vargs[1] );
      vargs[1].vt = VT_BSTR;
      vargs[1].bstrVal = ::SysAllocString( stupidstr );

      VariantInit( &vargs[0] );
      vargs[0].vt = VT_ERROR;
      vargs[0].scode = DISP_E_PARAMNOTFOUND;

      dp.rgvarg = vargs;
      dp.cArgs = 5;
      dp.cNamedArgs = 0;

      VARIANT  vret;
      VariantInit( &vret );

      EXCEPINFO  excepInfo;
      unsigned int index;
      hr = pValidation->Invoke( dispID, IID_NULL, LOCALE_SYSTEM_DEFAULT,
DISPATCH_METHOD,
                                &dp, &vret, &excepInfo, &index );
     ....

The Invoke is giving me an exception, and the exception is "Exception occured"
:-{
The dispID is correct(it's the Add 0x00b5(181)).

I've tried many combinations to no success.  (I tried reversing the parameters
like above.
I've tried ignoring the last(first!? :-/)  argument since it's not needed in
this example.)

Thanks,
-DaveS

ps.  Don't tell me to import.
pps. Don't tell me to use the OLEDispatchDriver(though it works in this case.)