음.. 날짜 기간 계산하는 프로그램 만들고 있는데..

이번에도 에러가 나네요.

procedure TfrmInfor.Button1Click(Sender: TObject);

var
   CHKDATE, FDATE, TDATE : TDateTime;
   YY, MM, DD : LongInt;
   CHK : INTEGER;
begin

   FDATE := strtodate(formatmasktext('####-##-##;0;', maskedit1.Text));
                             ---------------- -> 요 부분이 에러인것 같아요.

   TDATE := strtodate(formatmasktext('####-##-##;0;', maskedit2.Text));

   CHK := 0;
   IF (MONTH(TDATE) < MONTH(FDATE)) OR ((MONTH(TDATE) = MONTH(FDATE)) AND (DAY(TDATE) < DAY(FDATE))) THEN
   BEGIN
        CHK := 1;
   END;
   YY := YEAR(TDATE)-YEAR(FDATE) - CHK;
   edtYear.TEXT := INTTOSTR(YY);

   CHK := 0;
   IF (MONTH(TDATE) <= MONTH(FDATE)) AND (DAY(TDATE) <  DAY(FDATE)) THEN CHK := 11;
   IF (MONTH(TDATE) <  MONTH(FDATE)) AND (DAY(TDATE) >= DAY(FDATE)) THEN CHK := 12;
   IF (MONTH(TDATE) >  MONTH(FDATE)) AND (DAY(TDATE) <  DAY(FDATE)) THEN CHK := -1;
   MM := MONTH(TDATE)-MONTH(FDATE) + CHK;
   edtMonth.Text := INTTOSTR(MM);


   CHK := 0;
   IF DAY(TDATE) < DAY(FDATE) THEN CHK := 1;

   CHKDATE := ENCODEDATE(YEAR(TDATE), MONTH(TDATE) - CHK, DAY(FDATE) );

   DD := STRTOINT(FLOATTOSTR(TDATE - CHKDATE)) + 1;
   edtDay.TEXT := INTTOSTR(DD);
end;

end.




에러가 머라고 나냐면..
요로코롬 난답니다.

'[Error] uInfor.pas(72): Undeclared identifier: 'formatmasktext'
[Fatal Error] pstudent.dpr(7): Could not compile used unit 'uInfor.pas' '



아참 ! 글구 아까 답변해주신님. 정말 감사합니다. ^-^
이번것두... ^^;