Creating PM Notification with reference to another Notification

Dear Guru's,

I want to create a PM notification with reference with another notification number. I am calling the bapi ALM_PM_NOTIFICATION_CREATE, able to create the
Notification but the reference notification number data is not copied to the created Notification.

ls_header-refobjectkey = '000012036419'.

ls_header-refobjecttype = 'BUS2038'.

ls_header-refreltype   = 'REFZ'.


call function 'ALM_PM_NOTIFICATION_CREATE'

    exporting

      notif_type               = lv_notif_type

      notifheader              = ls_header

      sender                   = lv_sys

   importing

     notifheader_export       = lv_notifhead

Advance thanks for the update.

Regards,

Sahu