I am trying to write a function that will count up the number of times an
occurence happens according to how long something took.

Basically I have a column that subtracts how long a phone call took, it
subtracts time B from time A to get a certain number of hours and minutes and
that column is formatted to display 00:00 (hh:mm).

I need a function that counts how many calls took < 20min, 20-30min,
30-60min, 60-120min, & 120min. I have gotten the function to work just
looking at one cell, but when I give it the range of cells in that column I
get an error.