Generally when looking at the leave usage (Such as the amount of sick or annual leave taken), most customers use the wagetype reports. This is because individual wagetypes are held in the payroll results for each leave type.
Reports can simply be run on those particular wagetypes. See under the Payroll Questions – ‘What options do I have for analysing payments’ for more detail on the options here.
The leave reports in the Generic Reporting Toolkit, concentrate more on reporting the current leave balances for an employee, rather than what leave was taken.