iPad Air won't charge even though adaptor and cable are working fine.

I have a charging issue with my 9 month old iPad Air (running iOS 7.0.3). My 12W power adaptor is no longer charging my iPad. I know that the problem does not lie with either the adaptor or the cable because they are charging my wife's (identical) iPad without any problem. I have tried charging from both my laptop and a variety of mains sockets. The current scenario is as follows: if my iPad is completely drained, I connect the charging cable and the charging symbol (i.e. large white battery with red strip at the bottom) appears. So far so good. However, by the time the iPad comes to life and displays the 'slide to unlock' screen, it says 'Not charging' next to the battery icon in the top right-hand corner. Beneath the time on this screen, it says that the iPad is 1% charged and it never goes beyond that no matter how long the charging cable is left in. When I remove the cable, the iPad drains rapidly and goes dead again. There is no obvious damage to the iPad - as long as it is connected to the cable, I can unlock the machine and access different functions in the usual way. I have tried powering off and 'resetting' via pressing home button and wake/sleep button at the same time, but it doesn't solve the problem. Any advice would be greatly appreciated. Thanks.