I have used facetime before with no issue on my macbook air. Recently I tried again and was getting the "there was an error in activation" message. Tried every solution with no results. I created another user on my computer, which facetime does work under. (Any help with that too would be helpful). Though when I try to reach people who I know have facetime enables, and have facetimed before, the option to call or video call are greyed out. What am I missing?