cl_usmd_ui_services~save method not creating change documents

Hi ,

We are creating a program for changing the CCTR Hierarchy and using  cl_usmd_ui_services~save after all changes are done .

Change documents are not getting created . Does any one know the reason for this ?

CALL METHOD lo_service->save
   EXPORTING
     i_mode     = if_usmd_ui_services=>gc_save_mode_draft
     io_model   = lo_model1
*    if_commit_work = 'X'
   IMPORTING
     et_message = lt_msg.