Calendar Management Codeunit

I have written a function to calculate the next working .

My parameters is Fromdate and No of Days .

GetTheNextDay(FromDate : Date;NoofDays : Integer) : Date

ToDate:=0D;
ToDate:=CALCDATE(FORMAT('<'+FORMAT(NoofDays)+'D>'),FromDate);
TempDate.RESET;
TempDate.SETRANGE("Period Type",TempDate."Period Type"::Date);
TempDate.SETRANGE("Period Start",FromDate,ToDate);
IF TempDate.FINDSET THEN BEGIN
REPEAT
  IF (CUCalMgmnt.CheckDateStatus(CompInfo."Base Calendar Code",TempDate."Period      Start",TempDescription)) THEN
 ToDate+=1;
UNTIL TempDate.NEXT =0;
END;
EXIT(ToDate);

Input:27/12/16,5

output:03/01/17;

it is giving one extra day

i have already checked my base calender in which there is only one sunday between my date range.

How is this possible?