hi i had same problem. is your radio not flashing so you cannot enter code?
found out simple cure on my nissan may work on others.
depends how many attempts you had depends how long you must leave/ but all you do is leave your ignition on (preferably in garage!) for average 2 hours and your radio will flash and request code DO NOT turn ignition or radio off or time will reset and you will have to wait again
also be sure you are pos on which button to press after code is inputted or again it will refuse and lock again
hope this saves someone some dough cos if you take back to dealer they will charge the earth for a "factory reset" when this is all they do
barry freeman
April 2010