Journal entry for A/P invoice

HI

After creating the A/P invoice,I am gfetting the journal entry as

P.N. Associated CREDIT

Service tax DEBIT

Goods Received Not Invoiced

I dont know why its coming wrongly eventhough,i made "Set G/L Accounts by ITEM GROUP".Actually the 'inventory account' is defined as PLANT & MACHINERY for that particular item group but this "GOODS RECEIVED NOT INVOICED" is defined in 'Allocation Account'.I dont know why its posting like this.....can anyone suggest