The leave problem was due to Holiday Set.
(which refers to different states enjoy different set of holidays, for example, Kelantan & Selangor)

For Holiday set to work, the staff must belong to a department where the holidays set has been defined.

In this case, staff Tan Pi Shen is in department NONE, which has no entry in the reference list of HolidaySet + Department pairs.

Solution:
——
A. Add department ‘NONE’ to one of the Holiday Set.

or

B. Change department of Tan Pi Shen to one of the
proper departments instead of NONE.