ASUS Ultrabook plugged in, not charging

Its ok if it is not charging, my Asus K55A does it all the time, it shows at "98% charged, Not charging" its fine. Generally when that happens, its a error with windows predicting how much battery percentage is actually on.

IF your really concerned, plug in to a full charge and discharge to 6-10% for two or three times, charging for 6ish hours between(or a night) and that should get make the percentages more accurate.
 
If the battery can charging and discharging , it also caused by the power management setting (over 60% or more stop charging). If the battery can not charging but can discharging it caused by the motherboard charging circuit failed. If the battery can not charging and discharging the reason is battery failed (also as the battery protect discharging board locked) just replace a new one.