Get Paramater ID not working

Hi together,

I am trying to use the GET PARAMETER ID, for various transactions. So, the code that I have written is:

CALL TRANSACTION 'IA05'.
    GET PARAMETER ID 'PLN' FIELD gv_plnnr.
    GET PARAMETER ID 'PAL' FIELD gv_plnal.


CALL TRANSACTION 'IA06'.
    GET PARAMETER ID 'PLN' FIELD gv_plnnr_r.
    GET PARAMETER ID 'PAL' FIELD gv_plnal_r.

In both the transactions the values of the ID PLN (Task List Group - plnnr) are fetched, but the values for ID PAL (Group counter - plnal) are not fetched. I checked and in both of them the parameter id for the field PLNAL is PAL.

The sy-subrc after the get paramter IDs is always 0.

Can anyone tell me why are the data not fetched?

Thank you,

R