Power Word: Shield Macro

[2Tall 1]

I am attempting to make a mouseover macro that will put Power Word: Shield on another player.  I am using the following:

#showtooltip

/cast [mod:alt,@player] [@mouseover,help,nodead] [help] [@targettarget,help,nodead] [] Power Word: Shield

The macro is bound to a key (#1 in this case).  When I mouse over any player (or NPC for that matter) and press the "1", all I get is a "hand" cursor.  It will not cast the spell.  What am I doing wrong?  Does this macro only work if you are in a party or raid?  I do not have this problem with Power Word: Fortitude spell as it works fine with the mouseover.

[Queliset 1]

Power Word: Shield can only be cast on members of your party/raid.

I've never seen a rationale of why they made it that way, but there you have it.

[Nazjul 1]

#showtooltip Power Word: Shield
/stopcasting
/stopcasting
/cast [@mouseover,help][@target,help][@targettarget,help][@focus, help][@player][] Power Word: Shield