Problem when registering two editor factories in one package.

Hi,

I have two custom editors that I register in one package by calling RegisterEditorFactory method. In Vs2008 everything works ok, but in Vs2010, when calling the method to register the second editor factory, an exception appears.  This happens as IVsRegisterEditors.RegisterEditor returns E_INVALIDARG HRESULT.
Why do I fail to register two editor factories in one package?

Thanks,
Ivan