Something goes wrong with my battery. My macbook pro is 2 years old. Last days, the battery goes lower and lower. When I put the power cord, does not charge at all, but just maintain the percentage of energy that already has! When I pull out the power cord, the battery goes lower. Then I connect the power cord again, once again, macbook pro does not charge, but it maintains the energy it has! So it seems that my battery stop charging. It can only be stable at the current level or go down. Can you please help me to solve this problem?