Counting time ranges within a range

I have a column of start times which are entered as per 24hr clock and what I am trying to do is to is to sort the times out into ranges;

00:01 to 06:59, 07:00 to 19:00 and 19:01 to 00:00

The range is T7:T488 and here is my first formula for 00:01 to 06:59 which works, it correctly finds 35 entries;

=SUMPRODUCT(--(T7:T488>=I496),--(T7:T488<=I498))-COUNTBLANK(T7:T488)

I have the time ranges set up for the two final formulas but I have massive negative values returned which is obviously not correct;

=SUMPRODUCT(--(T7:T488>=I497),--(T7:T488<=I500))-COUNTBLANK(T7:T488)

This returns a value of -289 whilst the other a value of -341.

I may have gone about it the wrong way as I am trying to do things without too much assistance but this has me stumped. I would be most grateful to be shown the correct way, thank you.