If the battery in the camera is more than a year old, it may be time to replace it. Lithium-type batteries do eventually age, and will not hold a charge. Take the battery out and with you to any store with camera batteries (most chain stores like CVS, Target, etc.) and buy a replacement.
If the battery is new, then make sure the charger is working properly. A technician at a repair shop can help you.
Good luck.
TooHotinAZ, August 2007