Is this considered custodial interference?

My mom and step father said that me and my brother couldn't go see our dad on a day that we were suppose to see him but my mom said that since she has let us see our dad on her days that its not considered custodial interference. We had a big argument the night before and they wouldn't let me talk to my dad to tell him that we couldn't see him. Me and my brother go to our dad's house on weekends and stay all weekend.