Trigger problem

Hey guys, i am trying to create a trigger that won't allow a table to be upddated on monday or tuesday. Can anyone tell me whats wrong with the code I have done for this?

Thanks

IF TO_CHAR(sysdate, 'dy') 'mon'|| 'tue' THEN
RAISE_APPLICATION_ERROR(-2015, 'error');
ENDIF

It could be case issue, try upper case

IF TO_CHAR(sysdate, 'dy') ='MON'
OR TO_CHAR(sysdate, 'dy')='TUE' THEN

Thanks for the advice. :)