Problem with database and login

Hi there,
I built a WordPress website in a sub-directory of my website (http://www.websiteA.net/test) to check it before to move it in my client’s old wordpress website (http://www.websiteB.com).

I made a backup of the “websiteB.com” database and all its wordpress file.
I exported the “websiteA.net/test” database then I imported all the file from “websiteA.net/test” WordPress into “websiteB.com”. After that I imported the A database in B database. I changed the (A) wp-config.php.

Now the websiteB is on line and everything is good but when I try to login, WordPress give me an error and then redirect me on “websiteA.net/test” login page!!!

How can I login in “websiteB.com” WordPress now???
Please help me!!!