$Q$4 = FIRST CALENDAR DAY OF MONTH
$BW$10:$BW$18 = HOLIDAYS

Using the formula:
=WORKDAY($Q$4,1,$BW$10:$BW$18)
I get the first workday of each month, excluding holidays, for some months,
but for others, it's moving ahead one more workday.

What the heck am i doin' wrong?