I have a hide(coolwhip bowl with a hole in the lid big enough for them to go in and out) in my tank that has coco bark in it and I moist it, my crested goes in it quite often especially at night, I also have two rock cave hides, and the smaller one gets used when I feed crickets, but the other he basically just crawls on, he doesnt go in it at all, so its more for looks.
they do move around quite alot, what this means is the vines and stuff you have is probably not enough cover for them to hide in close to the top of the tank.
You would want lots of ivy vines and flowers, not just vines....