Settlement Rule strategy for WBS

Hi Experts,

I am trying to create Settlement Rule for Investment Project.

I have activated the Account assignment 05 for Settlement to Superior WBS and have maintained in WBS settlement rule parameters.

My requirement is , for a bldg, Level 2 WBS represents floors which are to be periodically capitalized and only Level2 WBS has investment Profile assigned. Level 3,4 and 5 WBS's are to be settled to Level 2 WBS.

Level 2 WBS generates AUC automatically.

Challenge here is

1) LEvel 1 WBS which does not have any postings.

2) Should I have to maintain Settlement rule for Level 2 WBS manually in CJ20N or CJB1 to settle to AUC

3) How would I be able to check what settlement rule is generated for other Level WBS's

4) I tried to assign settlement rule to Level 2 WBS using FXA as Category, AUC created automatically as receivers ,but I do not see settlement type AUC ,only Full and PER is seen.

If I select PRE ,I get error Message no. KD085

Kindly guide me in maintaining the settlement rule for the above scenario.

Thanks,

Kehkashan A J