Using methods from a COM class in Delphi

I have a COM class created in VB.NET. I am trying to use it in Delphi 5.0.

I have seen some examples/questions on the topic, namely:

Call C# dll from Delphi

http://www.drbob42.com/delphi/headconv.htm

http://edn.embarcadero.com/article/32754

and others, but these all deal with basic functions and not custom objects.

Firstly, I have registered my VB.NET COM DLL using regasm.

My VB.NET COM object is defined as follows:

<ComClass(Bridge.ClassId, Bridge.InterfaceId, Bridge.EventsId)> _
Public Class Bridge

  ' A creatable COM class must have a Public Sub New() 
  ' with no parameters, otherwise, the class will not be 
  ' registered in the COM registry and cannot be created 
  ' via CreateObject.
  Public Sub New()
    MyBase.New()
  End Sub

  Public Function Quote(ByRef input As InObject) As ReturnObject
    BLABLA
  End Function

End Class

With an Input class:

<ComClass(InObject.ClassId, InObject.InterfaceId, InObject.EventsId)> _
Public Class InObject

End Class

And a Result class:

<ComClass(ReturnObject.ClassId, ReturnObject.InterfaceId, ReturnObject.EventsId)> _
Public Class ReturnObject

End Class

Please pay no attention to the class names and lack of code in them. I just want to highlight how I am defining them as COM classes.

I can't find any examples of Delphi code calling a method in a COM class, or one that uses custom objects as inputs and returns. But, from the examples I showed above, I thought the line in Delphi to declare the function for use would be like this:

function Bridge.Quote(i: InObject): ReturnObject; external 'Bridge.dll';

This fails to compile. I get an error:

function needs result type

Is there anything obvious that I am doing wrong?