The most likely cause of the absence days being incorrect on an absence, is the periods on the working schedule not being set correctly.
To check this, follow these steps.
Identify the employee's working pattern from their current career history record.
Under Employees, click Lookups.
Click Pattern, then Working Patterns.
Select the working pattern.
Click the Days tab.
Each day will have a working schedule associated with it, so make a note of each schedule.
Under Employees, click Lookups.
Click Pattern, then Working Schedules.
Locate the required working pattern, and click it to drill into it.
Click the Periods tab.
Ensure that the periods add up to 1 to signify a full working day. If both the morning and afternoon periods have 1 entered per period, your employee's absence days will double.