Embedded Interop REGDB_E_CLASSNOTREG error on client machine
See the question and my original answer on StackOverflowThere's not "magic" with COM, you must register the VB6 COM component (dll, ocx, etc.).
The interop .NET dll is not a COM component, it just contains metadata/binding from .NET to COM, so it doesn't need to be registered.
PS: in fact, you don't have to register, you just need to give clients a way to find you, so there's also the possibility to use Registration-Free Activation of COM Components: A Walkthrough, but it can be more work than simply register a bunch of dlls.