Yea, pine bark can be tricky. I remember climbing them with my homemade climber. I would jump up and down and wiggle back and forth to make sure the blade cut it deep and the teeth grabbed good. The trick (as I see it) is to have the tree belt tight enough to grap if you fall but loose enough so you can slide it up as you climb. I would suggest practicing to get the right tension. Stand at the base of a pine tree and connect the tree belt up as high as you can. Then drop....you will see if the belt grabs and you will also see what it will feel like to hang there. You might even set the base of your stand up or use a ladder so you can get a little higher. Just make sure you have somebody there to help you if you need it.

Happy and Safe Hunting
Reid