Time calculation in excel and conditional format

Dear all,
Few minutes ago I have posted a thread for your assistance; I do not see it in my post.
Therefore I am posting it again. I am trying to calculate over time. Condition only full hours combining time start before 8:30 and time stop after 17:00 will be counted for over hours. Fraction of an hour will not be taken in to account. Also on Fridays / Saturdays on overtime will be calculated rather will be paid on a fixed rate. The same for National Holidays. I also tried to use conditional formate in Column "G" to indetify Fridays and Saturdays. It works some how, but when ever I type anything in a cell of cloumn "G" it also give indication for Friday/ Saturday. Further If I delete any date in column "A" then, the corresponding cell in "G" also changed like indication for Friday/ Satire day. Is it so that an epmty cell represents a specific date/ day?

In the attached cell please note that in F8 or F9 it should give 1 hour instead of 0.

I really would be grateful for the solution.


Best regards,

Subhash