Timesheet IF statement woes

Hi

I'm trying to adapt the attached timesheet for my purposes, I can't remember where I originally downloaded it from.

Working Hours.xls

What I would like to be able to do is have it so that if D6 contains A (Annual Leave), S (Sickness) or P (Public Holiday) a positive balance of half a standard working day (contents of cell L1 divided by 2) added to 06. If G6 contains one of these letters it does the same.

I'm guessing it's something along the lines of:

=IF(OR(D6="S",D6="P",D6="A"),IF(K6>$L$1,K6-$L$1," ")+IF(OR(G6="S",G6="P",G6="A"),IF(K6>$L$1,K6-L$1$))

But I can't get it to work, my Excel knowledge is very rusty!

Any help would be greatly appreciated.