Number of Pay Periods in Range with SumProduct

Hi Folks,

I am trying to calculate the number of pay periods falling in between two dates, based off a table of pay period dates and coverage start / end dates. Sample spreadsheet attached.

=SUMPRODUCT(--(Payroll!$D$2:$D$27>='List of Enrolled EE''s'!B2)*(--(Payroll!$E$2:$E$27<='List of Enrolled EE''s'!C2)))

This is my working formula. It's correct some of the time but not all. I can't just add +1 to it, as then my correct numbers are changed too.

Sample Spreadsheet.xlsx

Thoughts? Thanks so much for your help!