Anyone else had problems with this ?

[China.Blue]

OK , OK , I know I shouldn't but what the hell. I can't get the cheat codes to work. Iam playing the ps3 version an enter the following as suggested by no less than 4 different sites.
I shall not give all the codes because I reckon of I can sort out one , it will do for the rest , but for " one shot kill " it says , while playing press and hold L2 , TRIANGLE , X , TRIANGLE , SQUARE , L1 , O.
I have tried and tried but nothing happens !!. Incidently , you hear a chime if you have done it right. Is there a glitch here or is it just me ???????