ALV Hierarchy Tree - Expand all levels by default

Hi users,

I am trying to expand all levels of an ALV Hierarchy tree in WDABAP using the method SET_EXPANDED of interface IF_SALV_WD_TABLE_HIERARCHY on the click of a button but it is expanding only first level of hierarchy and not the 2nd and 3rd . Is there any other change or property set that I need to do to achieve the same ?

Regards,

Rishabh