Plz Help Code Error

I want to format my N72 - after entering the code *#7780# it asks for code i enter 12345 it says code error so i go to Tools>settings>security settings in that lock code as i enter lock code it asks for the code so i type12345 then it accepts that and asks new code i give suppose11111 then again it confirms 11111 its set now again i come out of all this ...now i try to for mat my phone *#7780# it asks code i type 11111 it says code erroe then i try with 12345 it again says code error ...some one told to try last 5 digits if serial number it still dint work any one can solve my problem????