Maybe next time be the one to say hello and extend your hand for a firm hand shake. They will respect you more for taking the initiative and it will also say, "Hi, I'm here too...I'm not just right seat ballast."
Works every time for me. I've never had a problem. Or, maybe I just have been lucky? Also, as others have said, when walking through the terminal, don't be afraid to strike up a conversation with a 'mainline' crewmember. It shows that you have confidence in yourself, and it shows you are outgoing and appoachable too. You know, sometimes they are the ones that are the shy ones too...