acceptable ORA-12899

i executed an insert statment while an error rose up: ORA-12899 value too large (actul:69,max:64).

Then i found this value,and tested it.

create table TEST_LENGTH( A VARCHAR2(64));

select length('getNewB? ??÷???¤ M????°?? ?×?P·5??f?lient-Agent: CMREAD_Javami') from dual----return:64

 INSERT INTO CX_FUJIE.TEST_LENGTH
    select 'getNewB? ??÷???¤ M????°?? ?×?P·5??f?lient-Agent: CMREAD_Javami'
      from dual;-----error rose up: ORA-12899 value too large (actul:69,max:64).

could someone give me an aid?