Bingo, you are true genius

I have thought about this but I thought I already tested, and the number showed up right, a positive number. Now that you mentioned, I compared the two battery, the red,black line are backwards, man! what a surprise! I pulled the cord out and reinserted them as my old battery, it works! haha ...

But I already ordered this new phone:

http://www.buy.com/prod/vtech-dect-6-0-expandable-3-handset-cordless-phone-system/q/loc/111/218658159.html

Now I will have two phones, haha ...