Macbook Pro Retina – "Battery Is Not Charging"
This happens to me too. I clean the connectors, especially the area around the pins on the computer case. This is a very small area; last time I used a heavy paper stock card and cleaned out any dust or debris that might have been there. Problem solved!  This has happened to my computer a few times and the solution is always getting either the power connector pins clean, or the metal areas immediately adjacent cleaned. It could be a grounding issue.