(a) A broker's lien attaches to the commercial real estate interest owned by the person obligated to pay the commission on the date the notice of lien is recorded as provided by this chapter. The lien does not relate back to the date of the commission agreement.
(b) A notice of lien for amounts earned by the broker under an installment contract or under a commission agreement for a deferred commission is enforceable only to the extent that the installment or commission has become payable.