I noticed today that a silo seems to be worth a lot of granite (dunno why useless building imo) so i demolished the one i had recieved for retail pack and tried to accept an offer someone had posted of 2.2k granite for 1 silo but it kept coming up transaction failed so i tried refreshing the trade window and re-searching which still gave me transaction failed so then i tried refreshing the browser and still transaction failed.

So i gave up on accepting someone elses offer and made my own offer of 1 silo for 2.2k granite and within seconds the trade had successfully gone through.

At the moment it appears you can offer up a building for something and have it accepted successfully but you can't accept a request for a building.