unable to use DLL ActiveX with a form in a vc client

Hi,
I have create a dll activeX this dll have a class and a form.

if the dll have only a class, then i succeed in creating the activeX in the VC client.

if the dll have class and form, the VC client is unable to create an instance of the ActiveX

Any idea of the why and how resolve it!

Thx a lot!