Example PWM with Poti

hi together

i’m new on the xbee’s and try the example on the example site: PWM Output/Potentiometer Input.

i set the both xbee’s like the example. when i connect the TX xbee with power, the led on the RX xbee pwm out is going on. so i think the RF connection is working. but nothing happens when i change the value of the poti, the light is still on. but on the RX XCTU-Terminal i can see the value changes from poti.
when i disconnect the TX xbee from power, the led goes off.

Please can anyone give me a little hint?

Many thanks

Which XBee modules are you working with and which example are you referring to?