WotLK Macro Question

[motrcolt]

#showtooltip
/cast [nomod] Divine Shield;
/cancelaura [mod:shift] Divine Shield;

Just trying to make a macro that will cast divine shield and cancel the effect when I hit shift but that cancelling of the spell isn't working. Anyone know what I am doing wrong?

Thanks!

[lostnfound]

on who you cast DS with that macro is the real Question