Nokia 6620

Hi everyone, I have a nokia 6600 (same as 6620 except different frequency) with T-mobile and when I go under security and setting its asking me for a lock code, I tried the default 12345 and it doesn't work!!! I also tried formatting the phone by pressing the *3talk power combo and once formatted, it still doesn't recognize 12345 as its code. So if anyone can help, I would greatly appreciate it...