Druid New to Charming and Multiple Breaks - Advice?

[MasterGeoffrey]

Just got my Druid to 19, and of course everything feels pretty awesome. He can port now, new heal and DD, and charming in the Karanas is a hell of a lot of fun. But every so often I run into a problem, and I'm wondering if it's just random bad luck.

Sometimes I'll charm, say, a gorge hound, and sic him on another mob. Root the other mob for good measure. Charm on hound breaks. Recast, he makes it to me and interrupts maybe (still trying to get a gauge on how far away I need to be), but I finally re-charm, send him in, he immediately breaks again. (Promise I'm not hiding or casting Camo.) Root also breaks, so I take off, turn and re-charm, root mob, charm breaks yet again. I literally charmed him 5 times over this encounter and burned up all my mana. Both mobs are above 60 percent, so I bail of course.

I've read that there are no diminishing returns on charming mobs, but, as unlikely as this sounds even as I'm asking it, are there some mobs that have a higher likelihood to break charm on an individual basis? (Like this particular hound vs this other hound of the same name.) Is this just plain unlucky?

Also, what are your tips on handling situations like this better in the future? Just trying to get better at doing what Druids do.

Thanks!