about upgrading CI version

[eluser]kikz4life[/eluser]
hi,. i am optimizing a website in CI that has the version of 1.6.3 and thinking of upgrading the CI version to 1.7.2. Following the process in Upgrading CI version i encounter a problem. A Database Error occurred. I am able to access/login the website but when i click the other links in my main page this thing happen. I trace the problem when i copy-paste the system/database folder 1.7.2 to my website.

Is it just ok if i don't include the database folder in CI ver 1.7.2 to my website. Without including it, the website works fine. need some suggestion in this.

could anyone help me with this?
attach here is a picture of the said error.


thanks
-Dean