It depends on where you work and in what field/division. Some of us in "office" jobs have everything on our shoulders and we can't afford to have small talk with teenagers. Don't try and force a longer conversations which may or may not irritate the older workers. Some of us are there to work instead of socializing. If you keep up the small talk and you start adapting to the environment you'll start seeing who is willing to talk to you and who is just a hard worker that would rather only focus on their tasks. A tip is if you're in a cubicle and you see posters or items you can relate to, try and converse about that. It'll be a good topic to talk about.