Problem with the XBee S2B connected with Arduino Mini Pro

Hi folks,
How are you?
I'm working on Arduino Mini Pro and XBee S2B. I use an adapter to connect XBee S2B to Mini Pro (please check the attached picture). The connection is correct:
Mini Pro------XBee adapter
VCC -- 5V
GND -- GND
TX0 -- DOUT
RX1 -- DIN

I set this XBee as a Router. The coordinator was set on other XBee module.
There are no problems with the code, for sure.
But it failed to wirelessly transmit data.
Could you tell me what the possible reason is? Do I need to add additional module to Mini Pro or XBee?
Looking forward to your kind reply.
Best
J.

The XBee was set in AT mode