Error in Creating Level2 WBS using BAPI_PROJECT_MAINTAIN

Question

Hi All,
I am trying to Create a WBS-element at Level 2 of an already existing WBS-element using BAPI_PROJECT_MAINTAIN.
I suppose the 'hierarchy table' has to be populated for positioning a WBS in the structure. But I am getting the error 'The transfered hierarchy is inconsistent. Too many errors.'.
I desire to have the following WBS structure in place :
Project Definition :   PROJ_DEF
WBS for level 1   :   WBS1
WBS for level 2   :   WBS2 (This has to be at a sub-node of WBS1,and NOT at the same level as  WBS1)
Can some one give me solution to this error, and suggest a way to create the WBS in this pattern.
Regards,
Somil
I have written the following code to populate the hierarchy table :
  l_hierarchy-wbs_element         = 'WBS1'.
  l_hierarchy-project_definition   = 'PROJ_DEF'.
  l_hierarchy-up                        = ' '.
  l_hierarchy-down                    = 'WBS2'.
  l_hierarchy-right                     = ' '.
  l_hierarchy-left                       = ' '.
  APPEND l_hierarchy TO t_hierarchy_table.
  l_hierarchy-wbs_element         = 'WBS2'.
  l_hierarchy-project_definition    = 'PROJ_DEF'.
  l_hierarchy-up                         = 'WBS1'.
  l_hierarchy-right                      = ' '.
  l_hierarchy-left                        = ' '.
  l_hierarchy-down                    = ''.
  APPEND l_hierarchy TO t_hierarchy_table.

Answer 1

For create the network and the activity I use this:
***  NETWORK ACTIVITY
   wa_network-network = '000000000001'.
*  wa_network-network_type = 'PS02'.
   wa_network-short_text = 'Network'.
   wa_network-wbs_element = ld_wbs.
   wa_network-project_definition = ld_projdef.
   APPEND wa_network TO it_network.
   wa_projmethod-objecttype = 'Network'.
   wa_projmethod-method = 'Create'.
   wa_projmethod-objectkey = ld_wbs.
   wa_projmethod-refnumber = '000001'.
   APPEND wa_projmethod TO it_projmethod.
   CLEAR wa_projmethod.
   d_refnumber = '000001'.
   wa_activity-network = wa_network-network.
   wa_activity-project_definition = ld_projdef.
   wa_activity-wbs_element = ld_wbs.
   wa_activity-activity = '0010'.
   wa_activity-control_key = 'PS02'.
   wa_activity-description = 'Activity 1'.
   wa_activity-plant = '1000'.
   wa_activity-cost_elem = '0000705003'.
   wa_activity-purch_org = '1000'.
   wa_activity-pur_group = '100'.
   wa_activity-matl_group = '90'.
   wa_activity-constraint_type_start = '5'.
   wa_activity-constraint_type_finish = '5'.
   APPEND wa_activity TO it_activity.
   CLEAR wa_activity.
   wa_projmethod-objecttype = 'NetworkActivity'.
   wa_projmethod-method = 'Create'.
   wa_projmethod-objectkey = ld_wbs.
   wa_projmethod-refnumber = d_refnumber.
   APPEND wa_projmethod TO it_projmethod.
   d_refnumber = d_refnumber + 1.
   CLEAR wa_projmethod.