我用BHO做了个COM，可是老出错，请高手指点!!!

我的BHO做使用了shdocvw,mshtml类型库

本来没有 IETest:=pUnkSite as IWebbrowser2;
IH:=IETest.document as ihtmldocument2;
这两句运行无误，可加上后出现错：Project IEXPLORE.exe raised exception class EOleException with message '未指定的错误'.Process stopped.UseStep or Run to continue.


请指教!!分不够可以再加!!!!

代码如下：


function TIEBrowserHelper.SetSite(const pUnkSite: IUnknown): HResult;
var
CPC: IConnectionPointContainer;
IETest:IWebbrowser2;
IH:IHTMLDocument2;
begin
if Assigned(pUnkSite) then
begin

IETest:=pUnkSite as IWebbrowser2;//有问题？？？
IH:=IETest.document as ihtmldocument2;;//有问题？？？

IE := pUnkSite as IWebbrowser2;
CPC := IE as IConnectionPointContainer;
CPC.FindConnectionPoint(DWebBrowserEvents2, CP);
CP.Advise(Self, Cookie);
if Helperform = nil then
begin
HelperForm := THelperForm.Create(nil);
HelperForm.Visible := True;
end;
end;
Result := S_OK
end;