Xbee bootloader

Hi, I recently bought two Xbee S2C, but when I was trying to connect them to my computer using a USB adapter and XCTU, the program don’t recognize the Xbee. I was trying with different options like recovery tool and reset de Xbee, also pressing the Commissioning Button but It didn’t work. So, I don’t know if I am pressing the Commissioning Button wrong, because I did a connection between PIN 20 (AD0) with PIN 10(GND). Also, I saw a error that indicated that There is not Active Bootloader in the module XBee, so I don’t know how to active or install the bootloader in the Xbee. Thank you.

I used the same adapter for a Xbee 3 that I recibed some week ago. And It works, so maybe the problem is with the XBee S2C.