If you have submitted your Bid and have not heard back from the Marketer, or if you can no longer see an Offer that you wanted to Bid on, there can be a few reasons why:
Declined by Marketer - This means that the Marketer did not accept your Bid.
Deadline Missed by Marketer - This means that the Marketer did not act on your Bid. Once a Campaign has been filled, Marketers typically let the Bids that they did not accept expire instead of declining every one that comes through. This allows them to reopen the Bid if they need to fill additional spots for the Campaign later on. They are however being notified of all of the Bids that come through.
Offer Is Missing From Dashboard - If you received a notification for an Open Bidding Offer, but you no longer see it or can no longer submit a Bid for it, this means that the Marketer has decided to not move forward with receiving any more Bids for their Campaign.