IObjectWithSite - amidoinitrite?

[T800G]

I'm trying to do this error-free. I'm writing context menu shell extension that will navigate current Explorer window through IShellBrowser acquired through IObjectWithSite and so far I have this (omitting unimportant code): header file

class ATL_NO_VTABLE CShellTarget :
public CComObjectRootEx<CComSingleThreadModel>,
public CComCoClass<CShellTarget,&CLSID_ShellTarget>,
public IShellExtInit,
public IContextMenu,
public IObjectWithSiteImpl<CShellTarget>
...
private:
CComPtr<IShellBrowser> m_pShellBrowser;
...
};

and here I override SetSite method, but I'm not sure if this code is OK

HRESULT CShellTarget::SetSite(IUnknown *pUnkSite)
{
ATLTRACE("IObjectWithSiteImpl::SetSite\n");

IObjectWithSiteImpl<CShellTarget>::SetSite(pUnkSite);

if (m\_spUnkSite!=NULL)
{
	CComQIPtr<IServiceProvider>; sp = pUnkSite;
	sp->QueryService(SID\_SShellBrowser,IID\_IShellBrowser,(void\*\*)&m\_pShellBrowser);
	//verify m\_pShellBrowser etc...
}
else m\_pShellBrowser.Release();

return S_OK;
}

It's hard to find one representative code sample of IObjectWithSite and Google isn't that much helpful. (btw yea I know about WM_GETISHELLBROWSER hack) Help is appreciated.