MonthCalendar date highlighting

Question

Hey

I want to make my MonthCalendar control highlight all days that fit a specific condition - like highlight all day's except Saturday and Sunday. Now this is easy if I want to apply it to a short period of time, but I want to apply it to an indefinite number of months (literally mark all working days from this day forth). I've tried 
to do this by setting a SelectionRange where start is (Year,Month,Day) and end (Year+1,Month,Day) - I expected this code to highlight all dates from this date to the same date of 2012, but it only highlighted every 1st of each month.
How can I solve this problem?
Thank you.