Grand Theft Auto IV friendship problems with Dwayne?

A long time ago I killed Playboy X in the mission "The Holland Play" and saw on my stats page that it's possible to raise the like and respect of Dwayne. I've never been able to contact him because I never got an email from him to become his friend or whatever it says. But I need his friendship to get 100% completion. I think it's some glitch because I always get his voicemail and I killed Playboy X a real long time ago.. Can I get to him at his apartment or something else? and which apartment is his?