Chances are you've only set the rating spread for the seeks you see. To actually set ratings for a game you have to choose Custom from the drop down time menu. When you do, a Rating Options button pops up. Click that and now you can set the range. And it's not set and forget, I think you have to do it for every game; well except for rematches. Erik got annoyed at all the folks who set the ratings to only play people better than them. It was skewing the whole selection process. You should probably read this:
http://www.chess.com/forum/view/livechess/new-logic-for-auto-pairing-and-seek-graph
and this:
https://support.chess.com/customer/portal/articles/1622811-how-are-seeks-matched-in-live-chess-
How do I choose the rating of player I'd like to play in standard live? I've set mine to -100 rating and +100 rating but mines letting players outside of the two challenge me and it's pissing me off.