My charger is not working...

Hi,

I have a MBPro and I ofthen encounter problems charging it. When I plug it in it says "Not Charging", which means that my current energy source is the charger, but I'm not accually charging it. So my battery percentage will just stay the same. I have gone to my school's IT support many times, but they can't fix it either, so they gave me a new one. Now I get the same problem again.

Can anyone help???