getting error

I'm trying to install the guestbook but even though I followed and read carefully the instructions on this forum and on the manual by Jam'n of Procaz I still get the same error after I submit the infos in the Advanced Guestbook setup page:
MySQL Error : Cannot connect to database
Error Number: 1045 Access denied for user 'root'@'localhost' (using password: NO)
All the folder, sub folders and files are set to 777 chmod values.
Where's the mistake?
Please someone help me.

Check the database information you provided in the config.inc.php file.

I tried over and over with several combinations (I tried both inserting the general parameters such as localhost and root and some customized ones) but I get a blank page at the most. Could it be something that has to do with the guestbook folder path (mine is ../guestbook/advancedguestbook/guestbook) or my server admin?
It shouldn't be so complicated neither I am supposed to tweak so much. am I?

The message indicates that the supplied database information is wrong. Speak to your hosts about the correct information.