The GBI staff member was trying to execute transaction FB50, using Company Code US90, (Debit 700000, Credit XXXXXXXXXXWhen the accounts and amounts are entered, he was trying to save the entry....

The GBI staff member was trying to execute transaction FB50, using Company Code US90, (Debit 700000, Credit 300800). When the accounts and amounts are entered, he was trying to save the entry. However, the system reported error message "Account 700000 requires an assignment to a CO object". Can explain to him why this would happen? Most importantly explain what kinds of application control this is in SAP.