I don't think i quite have the hang of this yet....

I'm having problems when i tweet somebody and say "@whoever", it'll send but i can't recieve anything from them. Like for instance, i follow singers and stuff like that, and i go to say hey to them like "@gerardway: hey. how's life going?" and it'll send but i haven't had any tweets back. But everybody else can have conversations with him. Is it just me? Does he have to be following me or is there something wrong with my page? This doesn't happen just with him, it's with other people too... It's VERY frustrating.