Problem creating COM object with Delphi 5 UP1

Hello !

I'm a newbie in COM and I'm trying to create a COM object that use the
IDispatch interface. But when compiling, sometimes it completes and
sometimes it says there are 4 undeclared identifiers missing in my
implementation class : GetTypeInfoCount, GetTypeInfo, GetIDsOfNames, Invoke.
I use only the tlb editor and I don't modify the code myself. Is it a bug in
Delphi 5 ? Or I forget something ?

Thank in advance !!!!!!!!!!!!! (three days I'm in that damned mess ...)

Nicolas FRELAT,