Not charging says This accessory may not be supported

My son and I both have iPads and for some reason after about a month with a new charger (even an apple brand) our iPads will say, "This accessory may not be supported " and what won't work on mine will work on his. I am so tired of buying new chargers can you please help me? I even tried to do the answer I saw with one of the iPhone's that worked on mine. Holding down the dismiss button while taking the charger out of the iPad then putting it back in-- did not work..