hey guys, tryin to get a macro for my pally to put sacred shield on the focus. Not hard i know but what i want is when i change focus for the macro to reset so its not continually casting sacred shield on the focus.

here is what i have so far, any ideas would b great.
#showtooltip
/castsequence [@focus,exists] reset=focustarget sacred shield, null (doesnt work but thats what im looking for)

i want the reset to occur when my focus target is changed. any ideas on how to do this? on my druids i run reset=target because when i click on a toon to heal it does
/focus [target=mouseover]
/target [target=mouseover]
which is perfect to start the reset but this is on my main dps toon that i run the group from so i dont want it changing targets so when i click it only does /focus [target=mouseover] so it doesnt change my current target that i am DPSing on.

thanks