Are you using hte wall charger that came wiht yoru iPad? I don't know model numbers, but have an iPad3 and found that if I used my iPhone 4s charger on the iPad3 it either didnt 'charge, or charged VERY slowly. So I made sure that I marked my wall charger that came wiht the iPad 3 and only use that to charge the iPad. It CAN charge the iPhone4s, but the phone gets pretty hot pretty quickly so I only do it in emergency.
Hope this helps,
2012OC11 12:35 Sydney
You have to use the iPad charger to charge the iPad. The iPhone charger doesn't put out enough power to meet the iPad's minimum requirements.
If you're plugging your iPad into the wall outlet with its supplied charger and you're still getting a 'not charging' then you may have an issue with the charger. You might have an issue with the port or you might have an issue with the cable.
If you have spares you can troubleshoot. If not, you may want to make an appointment with your local apple store. Because if there is a problem with the port it's beyond a user fix. If it is the port and your iPad is under warranty, and there's no obvious signs of 'abuse or neglect' then the port going bad can be covered under the warranty.
The quickest way (and really the only way) to charge your iPad is with the included 10W USB Power Adapter. iPad will also charge, although more slowly, when attached to a computer with a high-power USB port (many recent Mac computers) or with an iPhone Power Adapter (5W). When attached to a computer via a standard USB port (most PCs or older Mac computers) iPad will charge very slowly (but iPad indicates not charging). Make sure your computer is on while charging iPad via USB. If iPad is connected to a computer that’s turned off or is in sleep or standby mode, the iPad battery will continue to drain.
Apple recommends that once a month you let the iPad fully discharge & then recharge to 100%.
How to Calibrate Your Mac, iPhone, or iPad Battery
At this link http://www.tomshardware.com/reviews/galaxy-tab-android-tablet,3014-11.html , tests show that the iPad 2 battery (25 watt-hours) will charge to 90% in 3 hours 1 minute. It will charge to 100% in 4 hours 2 minutes. The new iPad has a larger capacity battery (42 watt-hours), so using the 10W charger will obviously take longer. If you are using your iPad while charging, it will take even longer. It's best to turn your new iPad OFF and charge over night. Also look at The iPad's charging challenge explained http://www.macworld.com/article/1150356/ipadcharging.html
Also, if you have a 3rd generation iPad, look at
Apple: iPad Battery Nothing to Get Charged Up About
Apple Explains New iPad's Continued Charging Beyond 100% Battery Level
New iPad Takes Much Longer to Charge Than iPad 2
Apple Batteries - iPad http://www.apple.com/batteries/ipad.html
Extend iPad Battery Life (Look at pjl123 comment)
New iPad Slow to Recharge, Barely Charges During Use
Tips About Charging for New iPad 3
Prolong battery lifespan for iPad / iPad 2 / iPad 3: charging tips
iPhone, iPod, Using the iPad Charger
Install and use Battery Doctor HD
In rare instances when using the Camera Connection Kit, you may notice that iPad does not charge after using the Camera Connection Kit. Disconnecting and reconnecting the iPad from the charger will resolve this issue.