Re: CoCreateInstance and "Class not registered" error...

"Alexander Nickolov" <>
Tue, 8 Aug 2006 13:25:05 -0700
For starters, verify that CLSIDFromProgID succeeds and returns
you the expected CLSID, then verify the CLSID is indeed
present in the registry under HKCR/Classes. I see you have
an in-proc server, but does its threading model match the
client? E.g. is it Apartment- or Both-threaded? If not, you'll
need marshaling support for your interface(s).

Alexander Nickolov
Microsoft MVP [VC], MCSD

<> wrote in message

Hi all.
I've a dll COM server (commercial, not mine) and I need to implement an
interface from this dll.
I'm using VC6.0 and VC2005. With 2005 it's all ok but not in 6.0...

I create a simple atl object with:
ThreadingMode: apartment
Interface: dual
Aggregation: yes
And with Support ISupportErrorInfo checked.
Then in the so created class I implement the interface (right click -
implement interface) AddTypeLib... open the registered dll and select
the interface.
Then I use:
HRESULT hresult

hresult = CLSIDFromProgID(

AtlWrapper* simple;

hresult = CoCreateInstance(
(LPVOID *) &simple);
The same code in vc2005 works, but if I write this in vc6.0 hresult is
0x80040154 (Class Not Registered)...
I tried almost every CLSCTX_xxx in this call... nothing changes...

What can I do?

Thanks all,

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