If the hides are too open inside they probably do not feel secure enough. How big are the hides? How big is your snake? They tend to like smaller hides they can just barely fit their entire body into.
My bp actually lifts his favorite hide off the ground most of the time because its too small, but he loves it (and it's just made of cardboard) so until it gets wet or yucky, I'm gonna leave it in there for him.
Also, aspen is great, but doesnt really hold humidity, maybe try the coco husk substrate, or something similar. They are generally sold in blocks like this.
http://www.wag.com/reptile/p/exo-ter...te-7-qt-112380
Also, humidity between 50-60 is fine for non-shedding periods.
I'm still pretty new as well, so that's all I have to offer at the moment.