Marta owes Carly $5,000 under a contract for maid services that Carly performed. Carly owes her landlord, Alec, $6,000 in rent. Carly wants to assign to Alec the right to receive the $5,000 from Marta, but the contract between Marta and Carly contains a clause prohibiting its assignment. If Carly assigns the rights anyway, a court will most likely: