We're apartment locators, where properties agree to pay us typically one months rent for every successful client that we bring them to lease at their property. Lately, we've had properties that will ignore our invoices, some to the tune of ~$50K total outstanding. We have some properties with signed vendor agreements stating they agree to pay with net60 terms, but still we're struggling to find any way of enforcing these terms. Can we file a lien against a property for past due invoices?