Microbiology

I did a kirby-baur test or a disk diffusion method test, this evaluates the efficiency of a antimicrobial/bactericidal/disinfectant agent, by placing disks soaked in said antimicrobials on a agar that has been inoculated with a specific bacteria. A zone of inhibition around the disk indicates if the bacteria is susceptible to the disinfectant, while no zone indicates that it is resistant. My problem arises due to the fact that some disks have mold growth as opposed to zones of inhibition or just colony forming. What exactly does mold growth on specific disks indicate?