Adding A Time Total More Than 24 Hours

Hello, I am trying to automate a timesheet but cannot seem to calculate a total hours more than 24. I have looked in the help section of Excel but the suggestion it offered did not work.

I have attached a copy but simply put it is showing as follows :-

Mon Tue Wed Thu Fri Sat Sun
10:00 Rest 19:00 19:00 Rest 07:00 Rest
18:00 07:00 07:00 19:00

Daily Totals Weekly Total
08:00 12:00 12:00 12:00 20:00

Now obviously the total hours worked should be 44:00 and not the 20:00 that excel is calculating the result to be.

The cells are formatted as [hh]:mm

The Vertical formula used to calculate the daily total is :-
=IF(A2="Rest","",IF(A3<A2,A3+(24-A2),A3-A2))

The horizontal formula used to calculate the weekly total is :-
=SUM(A6:G6)

Any help you could offer would be greatly appreciated as to say I'm perplexed is a slight understatement.

Thankyou VERY much.