Crystal Reports error: A subscript must be between 1 and size of array

Question

The following function returns the "A subscript must be between 1 and size of array"-error when run in Crystal Reports XI. Any idea why and how to fix it?

Function (optional BooleanVar start := true)

DateVar Array reportdates := [
    cDate(2012, 10, 22),
    cDate(2012, 11, 15),
    cDate(2013, 01, 23),
    cDate(2013, 02, 20),
    // some more lines of dates...
    cDate(2014, 01, 02)
];

// Here is some code that sorts the array just to be sure.
// Removed from question

// Find index of last reportdate not later than today
NumberVar stopIndex;
for i := 1 to UBound(reportdates) do (
    if CurrentDate >= reportdates[i] then
        stopIndex := i
    );

DateTimeVar returnDateTime;
if start = true then (  // return start date
    NumberVar startIndex;
    if stopIndex = 1 then
        startIndex = 1
    else
        startIndex = stopIndex - 1;
//*** The error occurs here
    returnDateTime := cDateTime(reportdates[startIndex], cTime(0,0,0));
//*** The error occurs here
    )
else (  // return stop date
    DateVar stopDate = reportdates[stopIndex];
    returnDateTime := dateAdd("d", -1, cDateTime(reportdates[stopIndex], cTime(23,59,59)));
    );

returnDateTime;

Note: I found that the above function returns an earlier stop date than start date if run before the second date in the array. I rewrote the function to counter that and then I did not have a situation that produced the error in question, but I would still be interested in why the error occured in this function and how to handle it.

Answer 1

NumberVar startIndex;
if stopIndex = 1 then
    startIndex = 1
else
    startIndex = stopIndex - 1;

should of course be

NumberVar startIndex;
if stopIndex = 1 then
    startIndex := 1
else
    startIndex := stopIndex - 1;

and now it works...

NumberVar stopIndex;

should also be changed to

NumberVar stopIndex := 1;

to avoid errors if report is run before first report date.