I have a compaq evo n400c. New Battery does not recharge.

I have a compaq evo n400c. just bought a new battery cause the old one was not charging at all. However it was working with ac power. now it is showing battery life at 50% and i pluged the ac adapter and it is not showing no indicator of charging and shows to be running on ac power. The charging light does not come on no matter what i do. Tell me if it is normal and when would the recharging resume.