How do you interact with celebrities? "Attempt Introduction" Failures

My usual tactic is getting a conversation going with sims in the vicinity of the celeb. Most of the time the celeb will join in, so if you keep the chatting going long enough you will have him/her in your relationships panel, with the attendant ease of social interactions. This has proved very successful, and in one case has produced a high level friendship. None of my sims has any fame, either, not a smidgen.