Stopping mc from timeline?

I am having a nagging problem of not being able to get a mc to stop.
I have tried
_root.mcBreif.mcHead.stop();
and this.mcHead.stop();

The mcHead instance is a mc of a guy talking and I want to just tell it to stop when it gets to points and play at other points of the mcBreif timeline.

Easy… done it dozens of time… it just won’t work…

Could it be the because I am working with scenes? I havn’t done the scene thing much before.