Seems like many people are having this issue. I've disabled the trade to prevent further buyer dissatisfaction.

http://pasteboard.co/29Cd6bdu.png

Please get the gift sent or keys returned to the buyer. Thanks!

I believe you need to provide a game to your bot as it cannot send friend request.

Also, there is another new Steam change that is blocking bots from sending trade offer (it is probably one of those "limitation" that our bot accounts cannot fulfill), or just a temporary Steam problem.