When you mean expires, do you mean that after you've been in the trade long enough it cancels? That's naturally what happens to avoid on single player taking up an entire bot when someone else could be wanting to use it. It's all due to it being on a timer once you start the trade.
If this is not the case and you can't connect to the bot for a trade at all in the first place, then I currently don't have an answer available to you. You'll have to be patient until the owner can do the research and make a response confronting the issue to your problem.
Thank you for taking the time to report your problem.
