Hi,
Could you please let us know how you have maintained the half day unpaid absence.
You must create half day unpaid absence as a separate absence type (in PA30 if you consider full day absence and at the time field you put 4 hours, that will not consider as half day salary deduction).
Please check your absence valuation configuration -
1. V_T554L - absence valuation rule should be there
2. V_554S_G - assign your absence type half day unpaid absence with proper absence valuation rule.
3. V_T554E - Check for the proper counting class
4. V_T554C - in this table for your absence type put 50 in the percentage field of "Form Counting Classes".
Hope it should help.
Cheers
Anwii...