Coma and Allies

This is kind of a dumb one, but I need official clarification for a friend of mine.

So, here it is: Can you choose Coma as your strike against an ally (I presume no, as per cardtext). If you can, what happens?

No you cannot, coma can only target opposing vampire, allies aren't vampires. Same as how you can't play taste of vitae or disarm against allies either.

Name: Coma
[Sabbat:U, SW:U, CE:U, BH:PM3, Third:U]
Cardtype: Combat
Cost: 3 blood
Discipline: Dementation
[dem] Strike: opposing vampire goes into torpor.
[DEM] As above, and that vampire does not untap as normal during his or her controller's next untap phase.

Correct, can't Coma against an ally.