Check 'G/L Accounts By' field of each item in grpo,
If Set G/L Accounts By Warehouse, then map 'PURCHCHASE BALANCE ACCOUNT' in warehouse
If Set G/L Accounts By Item Group, then map 'PURCHCHASE BALANCE ACCOUNT' in Item Group
If Set G/L Accounts By Item, then map 'PURCHCHASE BALANCE ACCOUNT' in Item Master
regards,
Raviraj