Activation unsuccessful for imessage and facetime

So my grandfather bought an iphone 6s plus from Lazada . I could login to my previous icloud account but i could not activate my imessage and facetime . It is always either ‘ activation unsuccessful or an error occured during activation .I tried everything that i searched in google, waited for 24 hrs but i still could’nt activate my imessage and facetime in this iphone 6s plus. However ,i could activate instantly in my previous iphone 6s . So i tried checking this new iphone 6s plus for the coverage . It is written there ‘ Purchase not validated’ . So my question is could it be because of this ‘ purchase not validated ‘ causes my activation for imessage and facetime to be insuccessful? I really need help . Thanks