Hello erucvt; I am assuming that the USB extnesion was used to conenct the Keyboard and mouse to the console of the KVM swithc, and that is not a supported configuration. The Keyboard and mouse must be directly connected to the AV2020 console. I would recomend the LV1000 for the type of KVM extension with USB. You can cascade another AV2020 to your current AV2020, but a rwo port KVM would be a Switchview and would not be cascadeable to the AV2020. Best recomendation would be the LV1000.
Regards;
Danny