Hmm.. Dunno what to say. I use many similar macros and they work.

Can't do any testing atm since I am at work, but strange.

I know for a fact that a macro I use on my low level druid tank works

/castsequence reset=target xxx,null
/cast Maul

From recount I can see that maul gets casts. Don't remember what the xxx ability name was, but it was the melee AoE debuff. Maybe it works because I use castsequences?