problem with user login

[mrjameer]

hi

i transferred the 1.admin,2.staff and 3.client details from an old table to new table called users.when i login using admin username and password it is allowing me to login
similarly the staff,but when i login using client's username and password it is not allowing to me login.. even i enter the correct one.

when the admin creates a new client(user),then that username/password is stored in db and i can login using that clients username password.but  with the old users,i cant login, it is displaying blank screen.it is not getting the old users data.

here the user id is autoincrement,but i have dumped the id from other table along with usernams/passwords.


when i  try to create a new user with same old username and password it is saying that user already exist with that name.here iam using $HTTP_SESSION_VARS,php 4.3.6 and mysql 4.the session_start is in begining of login script.if i use $HTTP_SESSION_VARS is there any other thing i have to add to work with it.any your help will be appreciated.can you guess why it is.

thanks
mrjameer