wp-login redirecting

i’ve recently followed the instructions on http://codex.wordpress.org/Moving_WordPress#On_Your_Existing_Server to move my site from one folder to another on my webspace. the new site is functioning and links are working, but i have a problem in that i can no longer log in to WP at the old address.

in line with the instructions, i used cpanel to duplicate all the files from the old folder, which i then downloaded and uploaded to the new one, so i thought the old folder would stay functioning while i run tests …

however, when i try to log in to wp-login.php in the old folder, i am being asked to install WP.

could this problem be because the blog are now associated with the same MySQL database and user ?

is there some way to fix this so i can access the original dashboard and have the old site still functioning for a while ?

thanks !