problem to create DB User


How can i create a database user in Classic with SQL. When i'm trying to create  a db user its throwing an error like "The microsoft dynamics nav classic and SQL server security systems have not been succesfully synchronized. The Sql server login ****** does not exist on the ********server".

I tried to synchronize like NAV Tool----->Security----->synchronize all logins.....

but its not working.

Please help me to find a solution on this