Trigger to Concatenate

[PAVB]

I think problems go beyond a trigger issue... look...

SQL> -- This is your code... 
SQL> 
SQL> select to_char(sysdate, "Mon. DD, YYYY: ") from dual;
select to_char(sysdate, "Mon. DD, YYYY: ") from dual
                        *
ERROR at line 1:
ORA-00904: "Mon. DD, YYYY: ": invalid identifier

SQL>
SQL> -- How about this?
SQL>
SQL> select to_char(sysdate, 'Mon DD, YYYY') from dual;

TO_CHAR(SYSD
------------
Apr 23, 2010

SQL>

... do you see the difference?