Bug or not? InMonthToDate function

[#1]

= inmonthtodate ( '2006-04-25', '2006-05-30', -1 )

returns -1 (true), which is to be expected.

But

= inmonthtodate ( '2006-04-25', '2006-05-31', -1 )

returns 0.

May has 31 days. and April has 30. Same behavior is manifested when using any two months which follow one another and in which one has one day more then the other.

I'm using InMonthToDate function in a dashboard chart which compares this months sales to the previous months. When today's date becomes 31. graph is empty because quantity is always multiplied by 0.

[#2]

That's a thing I would definitely send to support!

The helpfile does not really state how Qlikview behaves in this case:

= inmonthtodate ( '2006-04-25', '2006-04-31',0) return 0 as well; maybe because the 31 does not exist in April..