Hermitage - theming bonus

[Jethro_82]

I can't get the theming bonus to work on the hermitage - do artifacts not count? I have an ancient era artifact from a city state a classical dutch piece and a modern polish - how is that not 3 different cultures and 3 different eras?

 

[BigChiefLizzy]

Artifacts don't count; it has to be three works of art.