I believe you can see the auction.
You cannot bid more money than you have. As of this writing, there are only a few horses where the bid is less than your bankroll. We should probably improve the error message you see. For a bid to be accepted, you must have enough money to cover ALL your bids in the current auction, not exceed the maximum number of high bids as specified by the auction, and bid higher than the current bid.
Let us know if you have more questions.