violin home practice and lesson - need help/advice!

Hello,

We started taking violin lesson (one to one lesson during 30 minutes, one time per week) one month ago. Brief summary - we already trying it for 8 months but after 4-5 lessons my son was losing interest and we stopped and then in a couple of months I tried again and again for 4-5 lessons - success and again loose of interest. But before my mistake was that we did not have regular home practices, very rare and irregular.
So now when we started I was trying to have short daily practices at home but it is not going very successful, very often it is just 5 minutes and that is it, my son does not want to play anymore (and also it is not every day, but I am asking him every morning to play violin but often he does not want). But he likes his violin, he is saying her good morning and good night, every day is checking whether she is ok and etc. I see that he likes the idea of playing, he likes to hear but for some reasons does not want to practice. First I thought that may be it will take time but at least our lessons with teacher are going extremely good. It was until yesterday. First 15 minutes it was as usual but then he started to run around, did not do what the teacher asked and so on. Teacher was changing activities all the time and it helped for a bit. But I am very worried now because we had it before, and I am sure that the next class would turm into nighmare and we would have to make a break again.

Could somebody please advice what I should do, how to motivate him to practice daily? And what to do at a lesson when he will start behaving badly?

My dd is 4. I have been teaching her piano. For us the biggest hurdle was establishing the habit of practicing every day. The first week she loved it. The second week she would cry. I made her do it anyway and stayed very consistent.by the fourth week of lessons, she plays every day. She seems to accept it as normal routine. The only time she gets whiny about it now is if I let it slip for a day. So, for us the key was consistency. By the way, it was torture for me making her play when she cried and whined. But, it was soooo worth it in the long run.