Maybe we can boil it down to a very simple situation. We have our buyer, who has resold to someone else who, for one reason or another, hasn't paid that buyer. That is an account receivable owing to the buyer.
Of course, if that account receivable is worth nothing because of the insolvency or bankruptcy of the person who dealt with our buyer, then, of course, there's no asset. It's an asset on the books, but it is of no value. Remember, this is a trust of assets actually received by or that the buyer is entitled to and can enforce the entitlement to. If the buyer has resold to somebody else on credit and hasn't received payment, that buyer has an accounts receivable, but if it's an accounts receivable that's worth nothing, then of course there's nothing for the trust to attach to.