I have a mid 2012 MBA and about half the time that I attach the charging cable, the green/yellow charging light does not come on. However, the screen brightens as if charging is happening, and the charging indicator in the menu bar indicates that the charger is connected. However, the battery charge percentage will not increase (but it won't decrease either, even with heavy use). It's almost as if it is "semi charging," that is, enough to keep the battery going at the present state of charge, but not increase the amount of charge. By detaching and reattaching the charging cable a couple of times, I can get the light to come on, and all is well. Two questions: 1. What's going on? 2. Is this likely an issue with the MBA mad or with the charger (not great, but better...) Thanks!