Macro for casting on target I'm already casting on

On my monk healer I want to always cast surging/enveloping mist on the target that I'm channeling soothing mist on. It seems to me that it's supposed to be this way by default, however when I'm channeling SM and I don't have a target or an enemy target and I try to cast surging mist, i only get a glowing cursor.

Edit: I use Grid and Clique, but I've disabled them and the same thing happens.