Service group PO got error while posting service sheet

Hi Experts ,

We have an issue reg Service Group PO , While posting the Service sheet , Business got error "147  account determination for entry OA01 WRX 0003

GRP  not possible " We have checked the valuation class  ****  that is not maintain i OBYC settings , But business not accepted RCA and even they given one successful scenario with that valuation class. 

I have checked in that successfully case PO  has maintain different items under service group . But this error case PO maintain different item .

1. Could you please let me know is there any configuration in service group items with valuation class .

2. Why the success case PO posted service sheet and GR and IR with valuation class ? That is not maintain in OBYC settings .

3.We have checked  OMQW , Services group maintain with empty valuation class

Thanks for your help in advance .

Regards,

Seshu