Point To Point with two Xbees Series 2.

I have two XBee Series 2 modules. I connected them to a voltage conversion chip to a PC (USB TO RS232). I use XCTU software and can communicate with the modules (read and write). Firmware version is 1220.
Both modules are connected just by four Pins (Data in, Data out, +3V (stabilized) and GND).

I want to communicte between only both of them and when i try to change the “Function Set” to ANY other then “ZigBee ROUTER/END DEVICE AT” the module shut him selfe down (ON led is off) and Xctu writing “Write Parameters…Failed”

what can i do to make both of those Xbee’s communicate to each other?

i already configure two Xbee Series 1 to communicate with each other and want to do it with series 2.
my project on youtube:

i found on google that there is an option to:
RTS (pin 16) => 3.3V (pin 1)
DTR (pin 9) => GND (pin 10)
and then it is possible to update the module, but it aint works for me.