My cousin doesnt talk to me anymore why is that ?

we grew up together when we were kids for like 10 years he is 3 years older than me we were like best friends but then he left to canada because my uncle had work there so we added each other on facebook that was 3 years ago and now when i find him online i send him a message he doesnt reply for no reason at all and the same on skype,etc that problem started a year ago but we weren't mad from each other or anything....any thoughts ? really wanna know the problem