05 Aug 2008 at 11:54 - 2
Not really sure what you mean. If you've bought or unlocked the skill and you place it in your skill bar, as long as you have enough energy/adrenaline and are not under the effects of a shout prevention hex ([Ulcerous Lungs] [Well Of Silence]) then you should be able to use your command skills.
Maybe im getting the wrong end of the stick, could you elaborate a little bit?