Dear Sir 
 In this example I am calculating the consume time for the cars journey, my table structure as follow:

SQL> descr travel_table 
 Name                            Null?    Type
 ------------------------------- -------- ----
 J_START_DATE                            DATE
 J_START_TIME                            CHAR(5)
 J_START_TIME_STATUS                     NUMBER(1)
 J_END_DATE                              DATE
 J_END_TIME                              CHAR(5)
 J_END_TIME_STATUS                       NUMBER(1)
 J_CONS_DAY                              CHAR(5)
 J_CONS_HOUR                             CHAR(5)
 J_CONS_MIN                              CHAR(5)


In my form  I am using this code for calculating 
the consume days and consume hours and the consume minutes 

the code for the bush button as follow 
--------------------------------
when-button-pressed 
DECLARE
  ST_DATE VARCHAR2(10);
  ST_TIME VARCHAR2(5);
  ST_TIME_STATUS VARCHAR2(2);
  EN_DATE VARCHAR2(10);
  EN_TIME VARCHAR2(5);
  EN_TIME_STATUS VARCHAR2(2);
  DATA_RET VARCHAR2(50);
  CON_L    NUMBER(4) := 0;
  
BEGIN
    
    CHECK_DATE_RANGE(:J_START_DATE,:J_END_DATE);
  ST_DATE := TO_CHAR(:J_START_DATE,'MM-DD-YYYY');
  ST_TIME := RTRIM(LTRIM(:J_START_TIME));

  IF    :J_START_TIME_STATUS  = 1 THEN
              ST_TIME_STATUS :='AM';
  ELSIF :J_START_TIME_STATUS  = 2 THEN
              ST_TIME_STATUS :='PM';
  END IF;

  EN_DATE :=to_char(:J_END_DATE,'MM-DD-YYYY');
  EN_TIME := RTRIM(LTRIM(:J_END_TIME));

  IF    :J_END_TIME_STATUS  = 1 THEN
            EN_TIME_STATUS :='AM';
  ELSIF :J_END_TIME_STATUS  = 2 THEN
             EN_TIME_STATUS :='PM';
  END IF;

  BEGIN
    DATA_RET :=travel_time(ST_DATE,ST_TIME,ST_TIME_STATUS,
                           EN_DATE,EN_TIME,EN_TIME_STATUS);
    MESSAGE('Time Calculated='||DATA_RET);

   
    :J_CONS_DAY  := SUBSTR(DATA_RET,2,INSTR(DATA_RET,' ')-1);
         CON_L :=INSTR(DATA_RET,'H');
         CON_L := CON_L + 1; 
              MESSAGE('CON_L ='||'  ' ||CON_L);

    :J_CONS_HOUR := SUBSTR(DATA_RET,CON_L,INSTR(DATA_RET,' ')-1);
         CON_L :=INSTR(DATA_RET,'M');
         CON_L := CON_L + 1; 

    :J_CONS_MIN  := SUBSTR(DATA_RET,CON_L,INSTR(DATA_RET,' ')-1);
    COMMIT;
  END;
END;
---------------------------------------
And the code for the function travel_time as follow:
---------------------------------------
FUNCTION travel_time (sd varchar2,st varchar2,s_ampm varchar2,
                      ed varchar2,et varchar2,e_ampm varchar2)
  RETURN varchar2
IS
  s_dt date;
  e_dt date;
  rtrn varchar2(50);
  ET1 NUMBER; -- Elapsed time
Begin
  begin
    s_dt := to_date(sd || st || s_ampm,'MM-DD-YYYYHH:MIAM');
    exception when others then
    MESSAGE('Invalid start date/time: '||sd||st||s_ampm);
    rtrn := 'Invalid start date/time: '||sd||st||s_ampm;
  end ;

  if rtrn is null then
    begin
      e_dt := to_date(ed || et || e_ampm,'MM-DD-YYYYHH:MIAM');
    exception when others then
      MESSAGE('Invalid end date/time: '||ed||et||e_ampm);
      rtrn := 'Invalid end date/time: '||ed||et||e_ampm;
    end;
  end if;
  if rtrn is null then
    ET1 := e_dt - s_dt;
    rtrn := 'D'||Trunc(ET1)||' '
          ||'H'||Mod(Trunc(ET1*24),24)||' '
          ||'M'||Mod(Round(ET1*1440),60);
  end if;
  return rtrn;
End travel_time;
-----------------------------------------
So my problem is when I run this form I am getting this message when I press the bush button

1) Invalid start date/time : 12-03-200310:30AM

2) FRM-40735:WHEN-BUTTON-PRESSED trigger raised unhandled exception  ORA-06502 

Can you please tell me what is wrong with the above code.



Notice :

The above code works fine if I change the 
NLS_LANG  from ARABIC_UNITED ARAB EMIRATES.AR8MSWIN1256 
To 
AMERICAN_AMERICA.AR8MSWIN1256
I have make this changed for NLS_LANG in the registry editor,But I required to use the NLS_LANG as 
ARABIC_UNITED ARAB EMIRATES.AR8MSWIN1256 
Because my form layout is Arabic not English 

Waiting for your valuable answer.

Best Regards

Jamil