iPad won't charge

Whenever I plug in my iPad to a general sync cable (like the same one I use for my iPod/iPhone), it simply says "Not Charging" in iTunes and it won't charge.

What's the issue? Isn't the sync cable used for iPad the exact same ones used for the iphone, ipod, ect?

I changed it out and used the included iPad sync cable, and it started working, but it looks exactly like the old iPhone sync cables.

So it hurts an iPhone to attempt to charge it on an iPad sync cable? But you can't go the other way? I'm confused.

The iPad draws more power than the iPhone. So despite the similarity in appearance, they must be different cords.

I'm told (from a MacWorld video) that the iPad can still charge on the lower power (older) USB2 ports of older Mac models, but only while asleep and only fairly slowly.

I do not think it would "hurt" an iPhone to use an iPad sync cable to charge it, the amperage would just drop down to the correct level for the device, but cords can't "amp up" beyond their rated capacity, so the reverse isn't true.

Even with the correct cable, lots of USB ports out there don't have enough power and you will see the "not charging" message when you plug in to synch. In most cases though it will charge when the iPad is asleep. This is the case with our iPad/laptop combo and from what I have read it is fairly common.