If it changes from Not Charging to Charging in like 2-5 seconds that is totally normal.
The notebook first Registers that the AC charger has been connected, looks at the power output of it, then makes the decission to start charging the battery.
If it stays like that, Not Charging, for an extended period of time, say 30 second or more, then you may have a problem with the charger or with the charging circuit in the notebook
FYI: It will also say you are not charging if the MacBook is drawing more power than the adaptor will provide.. for example, I am reading in a DVD - the DVD drive is pulling enough power that it has nothing left to charge with... after the drive shuts down, it switches to 75% and resumes charging...
-Traderhut Games (iPhone Developer - search for Traderhut - more games coming soon)
“I may receive some form of compensation, financial or otherwise, from my recommendation or link. <Edited by Host>”
Sorry about that, I shouldn't have added the search statement, the previous part was intended to introduce who I was, i.e. an iPhone developer. I did not provide any link, and currently the game that I have is free..
Of course, the non-signature part was intended to be helpful to anyone with this issue... I currently have '(not Charging)' displayed on my MacBook pro, so I imagine if you have it pulling enough power (perhaps doing lots of CPU intensive things), it might say 'Not Charging' at all times and you would have to stop said process in order to have it charge.