ActiveX events in C#

Question

I am trying to use an old ActiveX control in C#, and this line from CreateSink method

cookie = new AxHost.ConnectionPointCookie(ocx, eventMulticaster, typeof(TrueDBGridEvents));

will fail and generate an exception.

The exception is "Source object does not expose 'TrueDBGridEvents' event interface. When you look in the object browser the interface is there.

I can not find a reason why the ConnectionPointCookie will not find this interface.