Can't accept peace deal when offered by AI

[nashmilll]

I installed the game a few days ago and I'm playing with the latest patch. I got into a war with Brasilia, he came to me, offered the deal, I accepted, and just when I thought that we are at peace, next turn he attacked my explorer. I tried again to negotiate peace, we agreed, but somehow the game doesn't switch from WAR to PEACE. Can somebody help? If you need some more info, let me know. Thanks.