Error in activating Microsoft Office Home and Business.

I entered the key I purchased from Microsoft.com
My version of the Office 2010 is a trial version and I was planning to activate it once I purchase the key.
Now that I have the key, I can't activate it. What may be the factors that caused this problem?
Can anyone help me find a solution to this problem?
Setup Error
The setup controller has encountered a problem during install. Please review the
Log files for further information on the error.
