Okay a few weeks ago my Macbook battery died and would not be recognised - it had an X through the icon at the top of the desktop and would not charge. Thinking the battery is dead I ordered a new one on from internet which has arrived today. However this battery is not being recognised either as there is still the X through the icon at the top and it is also not charging however if I press the small buton on the underside of the new battery it lights up 3 green lights so I am guessing there is a charge already in it but why is the Macbook not recognising the new or old battery? 
Thanks in advance.
Thanks in advance.