Does anyone know how to program the Retevis RB75 radios. I purchased 2 of these, the programming cable, and FCC GRMS license and all I have is a glorified (expensive) handheld radio without repeater capability. I have downloaded and installed the software and driver from Retevis website on Windows 8 and even tried Windows 11. Manufacturer stated not compatible with anything above Windows 10 but tried anyway. The software opens but will not connect to radio (COMM3). I get a message that states: "radio connect failed". I have ensured the cable connection is tight. Not sure what to do from here, except maybe request a refund. Any help would be very appreciated. Thank you.
