Battery not charging

So I plugged my charger into my MacBook to charge, it was at 6%. I've had it in for about 20 minutes and it hadn't changed, so I checked and it now says, 'battery not charging.' I've found if I unplug the charger and connect it again, it starts charging, but I'm just wondering why it might be doing this and how to stop it not charging.
Thanks in advance

I am having the same exact problem.. I've never had a problem with the battery until today... I have only had my macbook for 7 months now... any ideas?

Try resetting the System Management Controller (SMC). The following Apple KB article will show you how. Link

If that doesn't resolve the battery recharging problem, it may be a hardware defect or a bad battery. Since your machine is still under warranty, make an appointment with your local Apple store to have them look at it.

Regards.