iBook FW Battery Problem

[MacLuver23]

I have a Key Lime Firewire iBook. I went to The Wiz and they had two iBpook batterys on sale for $35.00, so I bought one. before I bought it I went online in the store, The Macs weren't connected to the internet so I had to use a PC (YUK!) I went to Apple's website, and searched for PowerBook and iBook battery information. I found a page with all the AC adaptors and Battery modle numbers ect. I looked under iBook FW and it showed a model number. I looked at the box in the display case (the iBook battery Box) My iBook battery and the store's iBook battrey were copyrighted 1999 so I checked the model numbers ON THE BATTERY ITSELF and they matched BUT, on the box it had a different number. I ended up buying the battery and bringing it home. I took out my old battery and put in the new one. I plugged in the AC cord, so the battery could charge. About an hour later I go to check on it. I open my iBook and Start it Up. Everything is ok. I am at the desktop and the Battery icon (I am using OS X) has an X on it. Sometimes this happens to my battery when I've just switched (I have 2 batterys plus the NEW one) So I unplug the AC cord and BOOM! The iBook shuts off as if there is NO battery connected to it. What is happening. I don't know if I can return it to The Wiz becuase I opened the box. Now the battery was new so Apple had a 1 year warenty on it. Should I got to the Apple Store? Go to The Wiz? or ANYTHING ELSE!? Thanks for reading. Reply back soon!