Shore landing?

[unmerged(136147)]

In my current game as Japan I just can't land on the Ceram Province (Indonesia).
I just this error noise when I click on it...

Are there any restrictions to landings that I'm not aware of? The Province has Mountain/Forest but I can land on other provinces with the same terrain so that can't be the issue

 

[unmerged(42621)]

Maybe you are in colonial war and Ceram isn't a colony. Who owns it?

 

[unmerged(136147)]

Yes that was the case. The Province was owned by Dutch East Indies (VIP) and I declared on one of it's unciv satellites.