Battery not charging

I have a 1998 aurora and I replaced the altenator and the battery but still the battery is not being charged. i not sure why it is not charging. I put it on a battery charger just to move it around but dies very quickly. It has to be something that is keeping my battery from charging does anybody know what the issue could be?

Check the basics: Loose ground wire(s), blown fuse, or a parasitic draw being caused by something as simple as a frayed wire causing the radio to stay on. I've also read somewhere that the antenna motor could be trying to retract the antenna, and the antenna could be dirty keeping it from retracting fully, causing the motor to stay on.
Assuming the connections to the battery and the new alternator are sound, those could be the next avenue to investigate.
I'm sure someone else will come along with a lot more knowledge to impart.
Also, check the threads, I've practically rebuilt my 99 from the "intel" here...it's a GOLDMINE!

Voltmeter. $4.99 at harbor freight.

With the key in run, engine off, check for power at the L-terminal. It is the red wire in the connector that plugs into the side of the alternator. It is turned on by the PCM. Make sure that connector is plugged all the way in. I know it is in a tight spot!

It is quite possible that the battery is bad. If you charge the battery and it dies as fast as you say then I suggest that you replace the battery. An alternator will maintain a battery and provide the voltage to run the car but it will not recharge the battery. Also If you say the car dies when the car is running then the suggestions made in earlier posts will help you diagnose the issue. It is also possible that the new alternator was damaged when you installed if especially if the battery was not at full charge when you put it on.