CoCretaeInstance 失败，但CoGetClassObject成功解决方案

CoCretaeInstance 失败，但CoGetClassObject成功
我写了一个组件，用CoGetClassObject可以成功使用，而CoCretaeInstance就失败了，好奇怪！

CoCretaeInstance代码：

CoInitialize(NULL);


		HRESULT hr = 0;


		IFirstCOM* pIFirstCOM = NULL;

		// 下面这句挂了，挂载ole32.dll里面。我自己的代码都运行完了。

		hr = CoCreateInstance(CLSID_CFirstCOM, NULL, CLSCTX_INPROC_SERVER, IID_IFirstCOM, (void**)&pIFirstCOM);

		if ( SUCCEEDED(hr) )

		{

			pIFirstCOM->ShowMsg(L"111");


			pIFirstCOM->Release();

		}


		CoUninitialize();

CoGetClassObject代码：

CoInitialize(NULL);


		HRESULT hr = 0;

		IClassFactory* pIClassFactory = NULL;


		hr = CoGetClassObject(CLSID_CFirstCOM, CLSCTX_INPROC_SERVER, NULL, IID_IClassFactory, (void**)&pIClassFactory);

		if ( SUCCEEDED(hr) )

		{

			IFirstCOM* pIFirstCOM = NULL;


			hr = pIClassFactory->CreateInstance(NULL, IID_IFirstCOM, (void**)&pIFirstCOM);

			if ( SUCCEEDED(hr) )

			{

				pIFirstCOM->ShowMsg(L"111");


				pIFirstCOM->Release();

			}


			pIClassFactory->Release();

		}


		CoUninitialize();

------解决方案--------------------
hr = CoCreateInstance(CLSID_CFirstCOM, NULL, CLSCTX_INPROC_SERVER, IID_IFirstCOM, (void**)&pIFirstCOM);

红色那个ID如果改成IID_IUnknown呢？
------解决方案--------------------
创建对象实例失败了