I use correct charger and the charger works fine. But my battery still doesn't hold a charge.

Have you ever used your battery until it is completely dead? If yes, please use a multimeter to test if the battery voltage drops below 1V due to overuse. If so, the battery has been permanently damaged and cannot be recharged. Note that such damage is not covered under warranty. 

To learn how to maintain the battery life, you can click here.