interface request to itself - doesn't work!

Hi,

I created new interface (IStreet) inside Type Library Editor (Delphi 5,
Build 6.18, UP1). Then I try to do the next -

function THouse.Get_mystreet: IStreet;
var
  u: IUnknown;
  s: IStreet;
begin
  result := TStreet.Create( self, nil );
  try
    s := result as IStreet;  // get exception EIntfCust !!!
  except
    s := nil;
  end;
end;

i.e. when I try to request IStreet interface through the same
IStreet interface it can't to find it !!!
But I can get IUnknown and IDispatch interfaces without problem.
I didn't change TLB file.
What is the problem reason?

Thank you,
 Alexander Zemerov

Sent via Deja.com http://www.deja.com/
Before you buy.