Grandson dose not want to know me.

I have a 4 year old grandson whom I was very close too until his parents spilt up and my son went away, during this time I would talk to him on FaceTime every fortnight and met him a few times, my son is now back and all he wants to do is be with his dad , if I try to talk to him on FaceTime he hets very upset, and recently when I went to see him with my son, he kept saying I was spoiling his day- I no, longer feel I want to see him again.