If you have the court records, you need to look at the court record for the date that you entered into your negotiation. It is possible that you entered into a plea of no contest and did not realize you would still have a conviction. Remember that you can order the court transcript to see if the court clerk made an error. If the transcript shows that the case should have been dismissed, you can go back to court to correct the error. Until you do so, you will have this conviction on your record.