COM IDispatch-＆gt;调用失败，错误为DISP_E_EXCEPTION

Question

我正在尝试调用IDispatch-＆gt; Invoke调用来获取IDispatch对象的名称，该方法失败，错误为DISP_E_EXCEPTION。 我想要获得的属性是“accName”。 以下是尝试执行此操作的代码：

HRESULT getParentName(IAccessible* pAcc) {
    IDispatch *parent;
    HRESULT hr;

 if ((hr = pAcc->get_accParent(&parent)) == S_OK) {
    DISPID dispid;
    WCHAR *member = L"accName";
    DISPPARAMS dispparams = { NULL, NULL, 0, 0 };

    VARIANT result;
    result.lVal = CHILDID_SELF;
    result.vt = VT_I4;

    hr = parent->GetIDsOfNames(IID_NULL, &member, 1, LOCALE_SYSTEM_DEFAULT, &dispid);
    if (SUCCEEDED(hr)) {
        //OK till now
        EXCEPINFO exc;
        UINT numErrs;
        hr = parent->Invoke(dispid, IID_NULL, LOCALE_SYSTEM_DEFAULT,
            DISPATCH_PROPERTYGET, &dispparams, &result, &exc, &numErrs);
        if (hr == S_OK) {
            MessageBox(NULL, result.bstrVal, L"Got the name", MB_OK);
        } else {
        //fails with error DISP_E_EXCEPTION
        // exception EXCEPINFO return nothing
        }

    }