What you are experiencing is being out bid by another user hidden Proxy Bid.
To give you an example of how our proxy bidding works:
When you bid on an English Auction, you can use our proxy bidding process. By default, you can bid the minimum bid -- this amount is displayed for you on the bidding page. However, you can also enter a higher maximum bid that reflects the maximum you're willing to pay for the item. This amount is always kept confidential from other Bidders. Our automatic bidding (Proxy Bid) software then enters the lowest possible Winning Bid for you. If another Buyer bids (in real time or by Proxy), we will automatically raise your bid until you are Winning or until you have reached your maximum.
If you wish to participate in an auction using a Proxy Bid, you can "Increase" your maximum bid at any time (even if you are winning the listing at the time). If you change your mind and want to increase your previous bid to a new maximum using the automatic Proxy bidding, just go to your Bidding Activity. Remember, your new Proxy Bid (your maximum) will change to reflect your final bid price, but your current Winning Bid will not increase even if you receive a confirmation notice stating that your bid may have been raised incrementally to the next Minimum Winning Bid amount.