How To Get An Yikatong (Transit Swipe Card)? (Beijing)

Hi all!

I hate to clog up the boards with my questions, but I didn't see that a thread had already been made about this, and I've been having so much trouble I thought this might help someone else as well.

Where can I get an Yikatong card?! I've looked around and everyone just says to go to a subway, but I've been to four and every time I ask they either say no, or they yell at me in Chinese. I even checked to make sure I'm saying it right, so I don't think that's the issue! ;) Is there a station you know for sure to try, or is this just a matter of persistence?

Thanks!