IOleCommandTarget & Invalid Variant Type

[toms]

Hallo~!

Warum kriege ich bei Zeile 11 einen Invalid Variant Type?

Delphi-Quellcode:

function HrExecCommand(ucmdID: cardinal; const pVarIn: OleVariant;
  var pVarOut: OleVariant; bPromptUser: boolean): HResult;
const
  CMDSETID_Forms3: TGUID = '{DE4BA900-59CA-11CF-9592-444553540000}';
var
  dwCmdOpt: cardinal;
  OleCommandTarget: IOleCommandTarget;
begin
  dwCmdOpt := OLECMDEXECOPT_DONTPROMPTUSER;
  Webbrowser1.Document.QueryInterface(IOleCommandTarget, OleCommandTarget);
  result := OleCommandTarget.Exec(@CMDSETID_Forms3, // Invalid Variant Type!!!!
    ucmdID,
    dwCmdOpt,
    pVarIn,
    pVarOut);
end;

Delphi-Quellcode:

procedure TfrmMyBrowser.GetAvailableStyles(List: TStrings);
const
  IDM_GETBLOCKFMTS = 2233;
var
  varRange: OleVariant;
  b: TBStr;
  a: PSafeArray;
  l, h, i: Longint;
  hr: HRESULT;
  NullVariant: OleVariant;
begin
  TVariantArg(VarRange).VT := VT_ARRAY;
  TVariantArg(VarRange).ppArray := nil;
  hr := HrExecCommand(IDM_GETBLOCKFMTS, unassigned, VarRange, False);
  //....
end;