Especially when you restore a database that was backed up on a different server to where you are restoring it to, a sql server database user can become detached from its corresponding login, which means you won't be able to login to the database as that user. To see if there are any users in this state and to fix the problem, you need to use the sp_change_users_login stored procedure.

exec sp_change_users_login 'Report' 
exec sp_change_users_login 'Update_One', 'dbuser', 'dblogin'

You can find more information about this SP on MSDN.