HR_INFOTYPE_OPERATIONS FM usage

Hi

the follwoing code is not updating the SPRPS field in PA0001 infotype. Can you plz let me know if there any mistake.... I have used MOD operation also.

READ TABLE it_p0001 INTO wa_p0001 INDEX 1.

IF sy-subrc EQ 0.

IF wa_p0001-sprps IS INITIAL.

wa_p0001-sprps = 'X'.

ENDIF.

CALL FUNCTION 'HR_INFOTYPE_OPERATION'

EXPORTING

infty = '0001'

number = lv_pernr

lockindicator = 'X'

validityend = '99991231'

validitybegin = wa_p0001-begda

record = wa_p0001

operation = 'COP'

IMPORTING

return = return.