Using COUNTIF to calculate number of period on a system at any given time.

I am trying to set-up a user count using the COUNTIF to help calculate number of people on a system at any given time.

Used the sample that I had found here in sheet 2 but somehow my validation is coming out with a "FALSE" throughout the whole checking even when it is a valid time-period/frame.

I have checked the formula and also the data type appears to be the same.

Not sure where else to check.