My child lived with me most of the year, but my ex husband and I have a court agreement that he claims him every odd year. Do I answer no to him living with me on here?

My Federal and State keep getting rejected because my son is listed on my taxes, even though I have him as a non dependent this year.  This has never been an issue in previous odd years, but for some reason it is this year.  He lived with me the majority of the year, but I am not claiming him per our agreement.  Do I need to mark "no" to the question of him living with me, even though I'm not claiming him?