Problem during Individual purchase order

Hi Expert ,

For last couple of days , I've been struggling to resolve the below mentioned issue regarding individual purchase order . I've gone through lots of thread regarding this issue , and tried all " trial and error " basis process , but the problem remains exists .

About , doing Individual purchase order scenario , maintain the necessary settings

like , strategy group in mmr3 - 20 , item cat. grp - BANC , item cat - tab , schdule line category - CB , ...

In , CB schedule line category , alternatively maintain a/c assignment category as , E & M , in OME9 also - alternatively maintain aac E & M ...

in OMWD - maintain valuation grouping code with company code and valuation area .

in OBYC , maintain VKA , VBR , VAX , VAY - these four account modifier with my valuation grouping code and valuation area .

did , lots of trial and error method but still problem exists .

it displays " not possible to determine a consumption account " , all the time .

Please , help me how to resolve it .

Regards

Patel