I cannot get a sneak attack on Dragons for whatever reason.
I can be invisible, 100% muffle, sneak maxed out, sneak eye completely closed...
and it still will not give me my sneak attack bonus.
Just a standard attack.

Granted it was a named dragon, acutally the first dragon you fight; on this character I just now started the
main quest at level 30 something. Im on PC running patch 1.4 I believe.

I have no problem sneak attacking anything else in the game.
I can even use shadow warrior to get sneak criticals in open combat.
but yet it will not let me sneak attack a dragon, even when I am stealthy, what gives?

How about fighting more than one dragon before you say you can't sneak attack one?

No it's impossible to attack any dragon. I've tried bow sneak attacks on Ancient dragons and regular melee sneaks on others, it doesn't matter if they're named or not; you simply can't do a sneak attack. I hate dragons in this game, they ruin it, I think. That's why on 5 of 7 of my characters I don't even have them activated because they ruin my fun.

I strongly disagree. I've gotten a x15 multiplier hit on the dragon at Autumnwatch Tower. Random dragons or MQ-related dragons maybe not, but saying that you can't sneak attack ANY dragons is false.

I've never been able to do it. Are you on PC or console?

WRONG. Dragons can be sneak attacked. One shotted easily by daggers. This has nothing to do with PC/Console or mods.

Dragons are cool.

PS3, but like udey said its got nothing to do wih console/pc.

Part of the OP's problem could be the actual shape of the dragons (boxy) vs how they "appear." Usually(with melee weapons) you will wind up hitting their tails when they are perched. Now you don't want to get real close to the tail because it is bigger than what you can see. If you touch the dragon they wake up so you really want to swing at the maximum distance your weapon allows. I learned this the hard way. The tail isnt a tapered cylinder, its more like a collection of rectangles.

ALSO- if the dragon is already in combat a sneak may not work. The sneak needs to be the first hit on an out-of-combat dragon.

Well conversely, you saying that you've gotten a sneak attack on ONE dragon would be the same as me saying that none can be attacked using sneak. Your's could have been an anomaly. And like I said, dragon's are a waste of time in this game I wish they weren't in it so in the long run it doesn't matter to me.

You can with a bow and a very lucky shot.

Ok as per Udey's recommendation I tried attacking from farther away.
I tried this on the first dragon you fight, he was in combat with other NPC's;
I used invisibility to remain hidden.
Got a sneak attack with the bow.
Got a sneak attack with a sword.
Got a sneak attack with a dagger.
(I reloaded between each)

It seems as though you must be stealthed before the dragon shows up,
and attack only from behind (they seem to notice you faster than other NPC's).
The dragon's shape was the key, it really is just a collection of rectangles,
so I was standing too close origionally, even though it did not look like it.

But there you have it. You can sneak attack a named dragon that is in combat,
with either a bow, sword, or dagger.