He may just not be hungry. When did you get him? Do you know when his last feeding was? Are you feeding a live or a dead pinky? Do you know what he was used to eating before you got him? Is he warm enough?

My snakes eat better in the morning or afternoon then they do at night, maybe you should try again tomorrow.

If the pinky is dead and it's been sitting for a couple hours then you should throw it out.

Please don't get yourself too worked up about it.