Af Maay

Last year, I started working with elementary students from Somalia (Bantu) ESL. They are wonderful children! I have a question,if any of you guys out there who might have some insight. I know there is a silent period when learning a second language, and I know the children are adjusting to new cultural and educational expectations etc... But I have two students who will not attempt to say anything to me in English (only bathroom). I do not speak Maay Maay (but learning), but the children look at me straight in the eyes and speak Maay Maay, and I explain that I did not understand, to speak slowly or show me something that will give me a clue.
Does anyone have an idea what is going on? Is it me, or rebellion, or can I do something to motivate them....Help?
Pizarro