Hmm, the macro should work regardless of where you are. This is my macro for earth shield. It either uses my mouseover, target, targetstarget and if none of those exist then myself.
Code:
#showtooltip Earth Shield
/cast [target=mouseover,help,exists] [target=target,help,nodead] [target=targettarget,help,nodead] [target=player] Earth Shield
Try changing yours to the following and see if that works:
Code:
#showtooltip Sacred Shield
/cast [target=mouseover,help,nodead] [target=player,help] Sacred Shield
Hmm, yeah maybe its a mouse thing. I only have a 3 button mouse and I don't use it for healing at all .. I just have 5 macros and I click the numbers for them and use the mouse for hovering, targetting and moving. But then thats the way I work.