I am not familiar with that status but here is code I have used to change the status of a WBS.
*&---------------------------------------------------------------------*
*& Form CHANGE_STATUS
*&---------------------------------------------------------------------*
form change_status changing p_out type ty_out.
data: lt_return type table of bapiret2,
ls_return type bapiret2,
ls_return1 type bapireturn1,
l_undo_status type bapi_user_status-user_status,
l_set_status type bapi_user_status-user_status,
lt_result type table of bapi_status_result.
l_undo_status = p_out-proj_status.
l_set_status = 'CMPL'.
call function 'BAPI_PS_INITIALIZATION'.
call function 'BAPI_BUS2001_SET_STATUS'
exporting
project_definition = p_out-pspid
set_user_status = l_set_status
importing
return = ls_return1
tables
e_result = lt_result.
refresh lt_return.
call function 'BAPI_PS_PRECOMMIT'
tables
et_return = lt_return.
read table lt_return into ls_return with key type = 'E'. "No binary search due to if statement below.
if sy-subrc = 0.
p_out-message = ls_return-message.
read table lt_return into ls_return index 2.
if sy-subrc = 0. "Reset message if this line exists.
p_out-message = ls_return-message.
endif.
else.
commit work and wait.
call function 'BUFFER_REFRESH_ALL'.
call function 'BAPI_TRANSACTION_COMMIT'
exporting
wait = 'X'.
p_out-proj_status = l_set_status.