Entered new product key and did not change

[Gene ONeil]

I have tried to enter the product key. What happens is that i enter the 25 digit key and the 20 digit existing key is still there. When i try to open excel it only allows me to enter 24, wont enter the 25th digit. When i try to enter the existing key it does not take the "zero" digit. Can you help?

 

[Dark Lord of Tech]

http://windows.microsoft.com/en-US/windows7/activate-windows-7-on-this-computer