The problem is that it actually is used for something else and your wow is confused - probably because you're using a mod like ctmod that gives you extra action bars. Do this...if your grounding totem is shift+h, hit escape on each character, then go to "key bindings", find an unused binding, click on it, then hit shift+h. Then click on it again and hit "unbind key".

Now, go rebind shift+h to that action bar however you did it the first time, and it will probably work now. ctmod especially is notorious for not unbinding keys properly when you set new keys up.