Service PO commitment assigned to statistical IO is not get reduced.

Question

PO is created with Account assigned to Internal Order stastically and Cost center as real cost object.  Wih PO creation we check commitment in system
According to standard SAP, at creation of PO, system creates commitment & while doing GR/IR, system should reduce PO commitment and increase actual by that amount.  Service PO  is created for amount 239200 USD with Account Assigned Category K, Item category D, Account assigned to Cost Center  & Statistical Orders (9 orders by approximate 11%  ) So, initially there is commitment of 26000 USD on each service order. However from March 2009 onward business has done GR and IR for this PO approximate 50000 USD but nor commitment have reduced neither any commitment line item were posted in system.
As a result of it, business actual budget is fully consumed by (Commitment + Actual) and while doing IR budget deficient errors is received.
Here main problem is, non reduction of Service PO commitment while doing GR and IR.
Tried below approch so far.
CoAr / Order type Comitment acitive, Costcenter updates commitment and GL is valid on delivery date. Service PO order unit is JOB and commitment reduction is based on value match with PO details.
In order to test really probelm is with Commitment updation or reporting. I checked COOI and COSP with reference to object no.
but there is only one posting in line item of original PO amount and  at total level there are two posting  one is origiona one and seocind is with zero amount. but in both total line item for one of the peiod quantity is incomplete even after clicking Final Invoice.
Even after final Invoice ticked thre is not commitment line item gets posted in system. Even I run RKANBU01 program.
This is quite strange, if some one can give me other suggestion to proceed further.
With Regards
Nitin P.

Answer 1

1.on Statstical IO there is only one PO commitment which posted when PO originally created. After that once you do GR/IR with refrence to that PO system should reduce that original commitment and post actuals. So, I mean here  while doing GR/ IR "Nor commitment is reduced neither any commitment line item were posted in system"
2. I mean here on ticking Final Invoice button system should ideally close original commitment of that PO, with this tick in system only original PO amount commitment line item is there  and no any addtional line itme gets posted with values.
  "Even after final Invoice ticked thre is not commitment line item gets posted in system"
I hope this would be clear. I due restrication in accss and Master data relevant issue,  I am not able to replicate exact scenario in other environment. Let me know any one else have different opinion / understanding this will helps.
With Regards
Nitin P.