That's how listia works, it displays the minimum bid that surpasses the previous bid. So If someone bid 100, and I bid 300, it will display as 101, and if someone else puts 200, it will display as 201. But I will still be winning the auction.
You bid however many credits that you put in the last time. However, you are currently winning at 256 credits. Your max bid is still set, so if it was, say, 300 and I bid 301, I would be winning. But if I bid 299, you would still be winning.