Bark in a bag should be moist...otherwise you'll have to soak it to use it the first time. Your dendrobium should have all brown and squishy roots removed. Soaking in water is okay if it's got some Physan or anti-fungal mixed in with a few drops of superthrive to help with root growth. Also, once cleaned and disinfected, I would recommend a bark mix with the smallest pot you can find. Let the den dry out between waterings. The most common mistake with orchids is overwatering. If you water more often and have bad roots alot, change your plants to more open mixes and clay pots. The clay will wick extra water away from roots. The dry rooting hormone can be applied, but you'll need to disinfect first...Before it straightens up it will probably lose all it's leaves. But with dens, as long as the canes are green you have no problem rescuing....it's when they are squishy I throw them away.
Also; most dens will throw new growths no matter what. If you do some research on here you will find what others have done in this situation. I have a few I nearly killed now adapting to life on a stick mount. I too used to be bad with rotten roots....i'm finally learning that neglect can be a good thing with orchids. lol