Most likely because you didn't give a correct answer for one of the questions regarding the job requirements.
For example, if there was a question asking if you are a resident of California and you answered "no" your bid would be automatically closed. Likewise, if there was a question asking you if can lift a certain amount of weight and you answered "no" your bid would be automatically closed. All of the questions must be answered a certain way for your bid to be accepted.
