Count Dates if it Belongs to a Certain Month

This video shows how to count the dates in a list. The dates have to be from a certain month that is interpreted as text. Instead of using COUNTIF, the solution uses IF and array to convert a column into text month which the IF will then check.

[@katelynmorris1371]

Hi, This works really well for what I need. However, for some reason if I choose a range down the whole column it wants to count a blank cell as December. Do you know why that is?